How to Choose the Right Stroke Length for Your Electric Linear Actuator

Selecting the correct electric linear actuator stroke length is one of the most critical steps in building a reliable motion control system. Whether you’re designing an automation solution, replacing an existing actuator, or sizing a new system from scratch, stroke length directly determines how far an actuator can move—and whether your project will function as intended.

Stroke length is often misunderstood or overlooked, leading to misalignment, mechanical stress, limited motion range, or premature actuator failure. This actuator measurement guide covers crucial topics such as what stroke length is, how to choose actuator stroke, and steps to avoid common mistakes in linear actuator sizing. By the end of this guide, you’ll have the knowledge resources and confidence to choose the right actuator stroke for smooth, efficient, and long-lasting operation.

Stroke length refers to the total actuator travel distance an electric linear actuator can move from its fully retracted position to its fully extended position. In simple terms, it is how far the actuator rod travels in a straight line during operation.

For example, a linear actuator with a 4" stroke has exactly a 4" motion range from fully closed to fully open. This measurement does not include other aspects, such as the actuator’s gearbox housing or overall device length—only the usable motion range of the shaft.

Understanding Actuator Travel Distance

An electric linear actuator operates by converting rotational motor motion into straight-line movement, often through a leadscrew or ball screw mechanism. This is how actuators move to result in controlled actuator extension and retraction, allowing the actuator to push, pull, lift, or position loads with precision.

Stroke length defines:

• The motion range your system can achieve
• The actuator’s usable travel window
• Whether the actuator can fully open, close, lift, or lower your load

Choosing the incorrect stroke length can prevent a system from reaching its intended end position or cause it to overextend into mechanical limits.

Why Stroke Length Is So Important

Stroke length affects far more than just movement distance.

• Mounting geometry and bracket placement
• Available space for installation
• Speed vs. force tradeoff
• Load distribution and alignment
• Actuator structural durability

In many motion control setups, stroke length is the difference between a smooth, efficient system and one that binds, stalls, or fails prematurely. That’s why understanding the importance of stroke length is crucial during the linear actuator sizing process, which would then be considered together with force and speed requirements.

Accurately measuring the required travel distance is among the most important steps in choosing the right actuator. This section provides a step-by-step, clear method on how to measure actuator stroke that can work for most applications.

A complete A-Z guide on how to select, test, and implement linear motion for any application. Written by engineers, for engineers.

Step 1: Identify the Start and End Positions 

The mounting position measurements of your application define the limits of motion your actuator must achieve. Determine the fully closed or retracted position of where the actuator will be mounted, and then the fully open or extended position is expected to reach. Always measure twice, ideally on different days or with a different method, to catch mistakes.

Practical Alternative Measurement Methods

Using at least two different measurement methods is always advantageous, as doing so helps to further validate that your selected stroke length is correct if both methods give nearly the same result. Having alternative measurement methods can also be handy to identify your start and end positions in case a tape measure won’t do the job. 

1. Flexible String Measurement 

Best for awkward angles and hinged motion, this method excels when a tape measure won’t sit straight because the actuator mounts are at an angle or partially obstructed. This is because the string naturally follows the true H2H path, even when the actuator isn’t aligned horizontally or vertically.  

Step-by-step: 

1. Use a non-stretch string, cord, zip tie, or thin wire. 
2. Attach or hold one end at the base mounting hole. 
3. Pull the string tight to the rod mounting hole (keep it taut, not sagging). 
4. Mark the string exactly at the center of each mounting hole. 
5. Lay the string flat on a table and measure the marked length with a tape or ruler. 

Tip: Repeat the measurement at both end positions (open and closed). If results differ slightly between tries, average them. 

2. Rigid Template Measurement 

When you want a rigid reference for the most repeatable and installer-friendly process, you can test-fit multiple times using this method. Using a rigid template removes errors caused by sagging tape measures or flexible materials. 

Step-by-step: 

1. Use cardboard, a paint stick, a wooden dowel, or a scrap aluminum flat bar. 
2. Hold it between the two mounting holes. 
3. Mark the exact mounting centers with a pen or punch. 
4. Remove the template and measure the H2H distance. 

Tip: Drill small holes at the marks so you can physically pin or bolt the template in place and confirm fit. 

3. Folded Paper Measurement 

If you have no tools and need to do a few quick checks, this method offers you a tool-less approach for fast measurements in tight spaces. This method works because creases lock in distances accurately and are easy to measure afterward. 

Step-by-step: 

1. Use stiff paper or thin cardboard (printer paper works in a pinch). 
2. Press one edge against the base mounting hole and crease it. 
3. Fold or slide the paper until it reaches the rod mounting hole and crease again. 
4. Flatten the paper on an even-surfaced table and measure between creases. 

Tip: Label each crease (Position A / Position B) so you don’t mix them up. 

4. Photo-Based Scaled Measurement 

Great for tight or unsafe areas, this method is useful when measuring directly is unsafe, awkward, or physically impossible. The effectiveness of scaling from a known dimension helps remove guesswork and allows for repeatable checks. 

Step-by-step: 

1. Place a ruler, tape measure, or known object (credit card = 3.375" wide) in the same plane as the actuator mounts. 
2. Take a straight-on photo (avoid angled shots). 
3. Use a measurement or CAD app to scale the image using the known reference. 
4. Measure the H2H retracted & extended lengths digitally.  

Tip: Take multiple photos from the same angle and compare results to reduce perspective error. 

5. Assisted Two-Person Measurement 

For long distances or overhead measurements where tape sagging causes errors, this method can greatly reduce human error. Using two or more hands reduces movement, sag, and alignment errors. 

Step-by-step: 

1. One person holds the tape/string firmly at the base mount. 
2. The second person aligns and marks the H2H retracted & extended lengths. 
3. Keep tension constant and level. 

Tip: Call out measurements aloud and write them down immediately to avoid memory errors. 

6. Physical Dry-Fit Validation 

If you already own an existing actuator (even the wrong stroke), using this method offers the benefit of visualizing motion in person. This method allows users to spot early design considerations by examining how the motion of an actuator interacts with the overall mechanism. 

Step-by-step:  

1. Temporarily mount the actuator using bolts or pins. 
2. Briefly extend/retract using electrical power (or manual override feature if available). 
3. Observe how much travel is still needed or unused. 
4. Measure the difference to estimate the correct stroke length. 

Tip: Never bottom out the actuator during testing — stop before full extension or retraction. 

Step 2: Measure the Travel Distance

To ensure the actuator does not hit surrounding parts, measure the available clearance and straight-line distance between the two positions. This measurement should always be taken along the same axis that the actuator will move. The resulting value is your minimum required stroke length and range for the given space limitations. 

Required stroke length = Open position - Closed position

Calculating stroke length examples:

• Closed position: 14.2"
• Open position: 10.2"

Required stroke length = 14.2" – 10.2" 

Required stroke length = 4"

Step 3: Account for Mounting Position

Mounting style has a major impact on the actuator’s stroke length. If the actuator is mounted at an angle or uses pivot brackets, the required travel distance may be longer than the visible movement due to geometry. Consider:

• Fixed vs. pivot mounting
• Lever arms or linkages
• Angled installations

In angled setups, the actuator often needs extra stroke to achieve the same output movement as a direct linear setup, similar to how the length of a triangle’s hypotenuse will be the longest side. 

Step 4: Check End-to-End Actuator Length

Most linear actuators have a different end-to-end actuator length while in motion. Because of this, stroke length alone is not enough—you must also verify that the actuator’s fully retracted and extended length fits within your design. The typical formula for calculating hole-to-hole lengths has a pattern of adding stroke length with an input bias length. This input bias length may change depending on which stroke length was selected, as it accounts for the other components inside, gearbox housing, protruding mounting points, wall thickness, etc.

H2H Retracted = Stroke Length + Input Bias

H2H Extended = Stroke Length x 2 + Input Bias

For Stroke Length less than 12" (PA-09 datasheet page 4)

A = Stroke Length + 4.53" 

B = Stroke Length x 2 + 4.53"

The example in step 2 indicates a required stroke length of 4" and space limitations from 10.2" to 14.2". We insert the required stroke length into the formula above to check if the PA-09 could work as a candidate that fits within the application space limitations. 

A = 4 + 4.53" = 8.53" 

B = (4 x 2) + 4.53"= 12.53"

Since 8.53" to 12.53" can still fit within the space limitations of 10.2" to 14.2", the PA-09 passes the aspect of end-to-end actuator length requirements. Adding washers, spacers, or fabricating custom mounting brackets can allow for smaller actuators to have the exact necessary buffer room to match the larger fitting space.

Step 5: Safety Margin & Limit Switches

It’s recommended to have a setup that will always shut off electrical power once the electric linear actuator has fully retracted and fully extended. Sizing an actuator that operates exactly at its mechanical limits for the required travel distance will trip the limit switches to ensure power shut-off at the end of travel. If you added a small buffer (typically 5–10%) to your required stroke length to prevent binding or tolerance issues, consider installing an external limit switch to shut off power in a similar manner.

Tips for Choosing the Right Replacement Stroke Length

If you’re replacing an existing actuator for a pre-existing application, here are a few steps to help you find the right stroke:

1. Check the Label: Most actuators list stroke length on the product label or the manufacturer’s datasheet.
2. Measure the Travel: Retract and extend the actuator manually to measure travel.
3. Compare Mounting Dimensions: Ensure the end-to-end actuator length of your new actuator can match the needs of your application.
4. Contact Support: If unsure, Progressive Automations’ technical support can help you in finding the most suitable model we offer.

Actuator Stroke Selection Checklist 

• Endpoints defined and mount points chosen.
• L_A and L_B measured (twice, by two methods if possible).
• Stroke calculated.
• Safety margin added.
• Verify retracted and extended end-to-end actuator lengths.
• Catalog chosen stroke length
• Clearance checked through full motion

Easily match your existing actuator to a compatible Progressive Automations model. Start by entering a model number or choosing a brand. 

Stroke length doesn’t just impact how far a linear actuator moves — it also affects the performance and overall behavior once fully integrated. Several other design factors influence how much stroke a mechanical system will truly need and how well the actuator will perform:

• Load capacity & durability
• Mounting style and geometry
• Speed vs. force trade-off
• Space limitations
• Application type

Load Capacity and Durability

Longer strokes cause the shaft to protrude outwards further and introduce more leverage that can magnify the effects of load disturbances such as wind, physical obstructions, etc. Compared to shorter stroke lengths of the same model actuator, the actuators with a longer stroke length may experience:

• Higher mechanical stress
• Increased risk of bending due to side loading 
• More overall vibration

In high-load applications, selecting a slightly shorter stroke with improved mechanical leverage can enhance structural durability and movement stability. Alternatively, selecting linear actuators with a higher load capacity for the added structural durability is a common strategy often used to compensate for the mechanical stress of having a longer stroke. 

Mounting Style and Geometry

Mounting style and geometry can affect load alignment and how the transfer of motion from the linear actuator is utilized. Because of this, mounting style significantly affects the length of stroke that will be required for installation. Common mounting bracket options include:

• Fixed-mounted/shaft end brackets: For mounting style without rotating ends, the shaft can extend and retract from the housing in a straight-line path while the rest of the actuator is mounted in a fixed, stationary position. This mounting style is commonly used to achieve actions like pushing and pulling an attachment head-on.  
• Pivot-mounted brackets: Allow for an actuator mounting style with rotating ends. Common examples, such as U-shaped and T-shaped brackets in applications that require angular motion.
• Shaft mounting brackets: This style of mounting bracket is mounted around the actuator’s shaft housing to provide additional support, help maintain the ideal alignment, and/or serve as an alternative mounting style. Depending on the stroke size, multiple brackets can be used on a single actuator.

Speed vs. Force Trade-off

The challenge of a higher load capacity model is that the gear ratios are often adjusted to a different configuration, which results in a different overall movement behavior. Many linear actuators are configured so that:

• Longer stroke models may have slower movement speeds
• Higher load capacity variants have gear ratios with reduced speeds
• No speed compromises for the higher load capacity requires higher operating voltage &/ current draw, power consumption, thicker wires, etc

Because of this speed vs. force trade-off, stroke length should be selected alongside performance expectations and not in isolation.

Space Limitations

In applications with tight space limitations, an actuator that combines a shorter stroke with clever linkage design may outperform a longer-stroke direct-drive solution. Long-stroke actuators need more room for both extended and retracted states. This is because the design of traditional linear actuators requires a larger shaft housing as an enclosure for the longer shaft. Compact installations often limit:

• The suitable retracted length that will fit within the space limitations
• Accessibility and ease of routing cables 
• Mounting clearance for mounting brackets, assembly, and future disassembly

Application Type

Understanding how the linear actuator interacts with different application types helps refine stroke tolerance. If the application type requires movement at an angle, the required travel distance may be longer than the visible movement due to geometry. Consider how:

• Lifting applications such as bed lifts need full vertical travel
• Doors and hatches need enough stroke to clear hinges
• Mechanical systems require lever arms or linkages 

In angled applications, the actuator often needs extra stroke to achieve the same output movement as a direct linear setup, similar to how the length of a triangle’s hypotenuse will be the longest side. 

Even experienced designers can make stroke miscalculations that result in selecting the wrong actuator stroke. Avoiding these common mistakes can help minimize downtime, save costs, and improve operational efficiency.

Under-Sizing for Stroke Length

If you plan on having your system undergo modifications or changes in size, choosing a stroke that allows for too limited an adjustment room can restrict the potential for future upgrades. Selecting a stroke that is too short results in:

• Incomplete motion
• Limited opening or lifting
• System redesigns

Oversizing Actuator Stroke Length

Even when the stroke length is correct, some projects fail simply because the actuator cannot fully retract within the available space limitations due to the housing being too large when selecting a long stroke length. Choosing a stroke that is too long can cause:

• Overextension problems
• Mechanical collisions
• Space and cost inefficiencies

Ignoring Mounting Offset/Geometry & Consistent Units 

Many stroke miscalculations occur when there is a design oversight of measuring only visible movement and ignoring angled mounting or pivot points. Mixing and rounding measurement units is also a common source of calculation errors. These variables need to be accounted for when selecting the stroke length of an actuator:

• Mounting hardware occupies space
• Angled installations travel on a different axis from head-on motion
• Using consistent units (all mm or all inches) reduces rounding errors

Overlooking Mechanical Tolerances

A stroke sized too tightly leaves no margin for the tolerance necessary to account for outside disturbances that introduce deflection, backlash, or misalignment issues. Consider the following: 

• Certain mechanical systems are designed with flex or have backlash 
• Manufacturers often have a build tolerance (+/- 3mm for many general actuators)
• Pivot points and brackets may have slight gaps to allow for rotation
• Fluctuating temperatures during winter/summer seasons can change the size of gaps, ropes/linkages, etc
• Output disturbances can occur due to wind, obstacles/obstructions, etc

Finding the right linear actuator for your automation project can be challenging. Our linear actuator calculator tools simplify this process by helping you calculate actuator requirements and match them to the most suitable model with easy-to-follow steps. Whether for home automation, industrial machinery, marine, or DIY setups, it provides fast and reliable actuator recommendations as a reference point for your needs.

Getting Started with Our Calculator Tool

This tool has a maximum width range of up to 100" and a maximum height range of up to 100". It is the user's responsibility to perform physical tests and measurements for further verification after using the calculator tool for making initial estimations and references. Something else to note is that the "A" and "B" mounting points that will display when you choose an actuator model are to represent the mounting holes of your actuator(s). This tool does not account for any mounting brackets that you may install in the finalized project.

Understanding the Physical Parameters

This tool will require the physical measurements of parameters such as the width, height, and weight of our trapdoor. The angle of how far the trapdoor will open is going to need some initial estimation. The mounting hole position for the shaft of our electric linear actuator(s) and the number of actuators we plan to use are factors that need to be predicted for simulation. By approximating the size, weight, and scale of the project, we can make predictions for what type of actuator can be used for simulation. Stroke length will be one of the variables that we keep adjusting until we find a suitable recommended product that pops up on the right side of the calculator tool.

Measuring Your Trapdoor

The next step is to measure the dimensions of the trapdoor project and find the weight of the door. For rough measurements, a measuring tape should be accurate enough. Weight for a trapdoor can be estimated by calculating its volume (in^3) and then multiplying it by the pound mass per cubic inch (lbs/in^3) value based on the materials it was made from.

Our demonstration uses an example wooden trapdoor with the following values:

Length = 32", Width = 37", Height = 32"

Weight = 113 lbs

Because most trapdoors have stairs or ladders going to the basement, there's usually not much limitation on height; however, we'll just use 32" to have a value that is the same as our length. The ideal angle of opening will depend on personal preference and user height; however, 75° will be used for our example trapdoor.

Entering the Values

After you have measured the trapdoor, plug the necessary values into the calculator tool. By estimating the scale of your project, you can predict whether one actuator will be sufficient for the simulator or if using two actuators will be better for larger and heavier trapdoors. For just one actuator, we want to have the actuator mounted as close to the middle as we can to keep the weight as balanced as possible and reduce any chance of offset or side loading. This also helps to ensure the trapdoor can raise evenly instead of hanging or drooping due to a lack of support on one side. 

If you were to use 2 actuators, you'd have one on the left and one on the right for support and balance. When multiple actuators are required to travel synchronously, we recommend actuators with hall effect sensors. This is because they have hall effect feedback that goes to a control box, which would then be able to make the needed corrections if one side travels at a different speed from the other. Differing speeds can sometimes happen from slightly unequal weight distribution or the speed tolerance from the DC motors (+/- 10%) in the actuators.

The PA-04-HS is the only standard actuator we sell with hall effect sensors from off the shelf; however, we're going to use one PA-04 actuator in this example and choose a 4" stroke length to start with. We'll find that the angle and the default mount position are not suitable, so we'll have to adjust those, or we'll need to choose a different actuator or stroke length.

Making Gradual Adjustments

To better visualize what variable changes have what effects, you may test out the simulator by making gradual adjustments to the variables that have flexibility. By lowering the opening angle to 24° or lower, the previously chosen actuator will work; however, the result will be an uncomfortable angle to climb in and out of the basement. In this case, we will return the angle to 75° for a comfortable opening angle. By changing to longer stroke lengths via trial and error, we're able to find an 8" stroke that works; however, the actuator will be located very close to the wall in the X coordinate. Only having a 2" gap can be awkward for some installation conditions and does not leave as much room for play or adjustments if we want to take into account mounting brackets for the future.

Adjusting For More Space

Choosing a longer stroke length allows for more options to have a larger working room that can help account for extra space to add mounting brackets in the future. Different models of mounting brackets, such as our BRK-01 and BRK-02, have different space requirements due to their dimensions. You may also fabricate your own custom mounting brackets if you prefer.

Leverage for Heavier Doors

If we find out that the weight of our door will become heavier than initially expected, this simulator can have the weight parameter adjusted.  If you find the simulator with orange and red lines indicated but no actuator displayed, it could be because the chosen actuator does not have enough of a force rating for the door’s weight. In this example, the actuator disappears when there is a weight of 152 lbs because it doesn't have enough force capacity, but it will reappear when the weight is 151 lbs. Using a longer stroke length can allow for more leverage to handle more force. Doing so will cause the "B" mounting point to stay the same while the "A" mounting point moves backward. Using a 12" stroke allows for a door weight of up to 162 lbs, while the 10" stroke could handle a maximum of 151 lbs.

For the full video of our calculator tool, feel free to check out our video below:

Electric linear actuators come in a wide variety of designs and stroke length variations, each engineered to meet specific performance requirements, environmental conditions, and space constraints. From compact micro units that fit into the tightest spaces to heavy-duty industrial models combining long stroke lengths with thicker walls and durable structural integrity, each category offers unique strengths and applications. Understanding the design and specialties of different actuator types—such as tubular, micro, industrial, mini, standard, track, and telescopic—can help narrow down which solution offers the stroke length variations and characteristics you need.

To compare our different models of linear actuators, we have our compare actuators tool and compiled a reference actuator comparison chart.

Micro Actuators

Micro actuators are designed for applications where space is minimal. Their small form factor allows for integration into compact systems, although this comes at the expense of shorter stroke length variations ranging from 0.5" to 12". Variants of micro actuators can excel at high precision positioning rather than heavy lifting and are often chosen for their lightweight construction and adaptability. 

Mini actuators

Mini actuators bridge the gap between micro and standard actuators, offering a balance of compact size and moderate force capabilities. Their design allows them to fit in applications with limited installation space while still delivering performance suitable for a variety of automation needs. Mini actuators offer flexibility while still having a larger window of stroke length variations from 1" to 40", making them a versatile option for medium-duty, space-conscious designs. 

Our online quiz can help guide you in choosing from our range of micro and mini actuators to find the most suitable model for your needs

Standard Actuators

Standard actuators are the most common and versatile category, designed for general-purpose use across a wide range of industries. They have a large range of stroke length variations from 2" to 40" with broad compatibility for control systems and easy integration into both simple and complex setups with feedback functions. Their balanced combination of performance, availability, and affordability makes them the go-to choice for projects that require reliability without specialized constraints. 

Industrial Actuators

Industrial actuators are built for heavy-duty applications that demand maximum force, durable construction, and high weather resistance, with stroke length variations from 1" to 40". They are engineered with robust materials and strong gear systems capable of producing forces that may exceed 3000 lbs. Many are designed with customizable mounting options and compliance with industrial standards.

Tubular Actuators

Tubular actuators feature a cylindrical housing that gives them a sleek, low-profile appearance, making them both functional and aesthetically pleasing. Their enclosed design often comes with higher ingress protection ratings, such as IP65 or greater, offering reliable resistance against dust and water. A tubular design allows for a more compact width and height in exchange for a longer overall retracted length, with stroke length variations from 1" to 24".

Track Actuators

Track actuators operate differently from traditional rod-style designs, using an internal sliding carriage to create movement within a fixed-length body. Because their body length does not change with the stroke, they are ideal for situations where extension space is limited. Because the moving carriage has multiple points of contact with a pre-defined path rather than being suspended in the air, this design enhances stability relative to its size, with stroke length variations from 6" to 60". Since the open architecture of track actuators is more sensitive to dust and water compared to sealed conventional designs, track actuators are better suited for indoor applications.

Telescopic Actuators

Telescopic actuators employ multiple nested stages of shafts that extend from within one another, much like the sections of a telescope. This enables them to achieve stroke length variations from 12" to 24" and maintain a long extended length in relation to not requiring a long-retracted length. Similar to lifting columns, they are often more mechanically complex but offer unique capabilities that traditional actuator designs cannot match, making them ideal for applications with severe stored space limitations. 

Our custom actuator solutions can be tailored for specific stroke
lengths, forces, and feedback options:

Choosing the right stroke length is the foundation of a successful motion control system. By understanding the importance of stroke length working together with space limitations, mounting geometry, and load capacity considerations in different application types, you can avoid costly downtimes and ensure smooth, reliable operation.

We hope you found this as informative and interesting as we did, especially if you were looking for guidance in choosing a suitable actuator stroke length for your application. If you have any queries about our products or have trouble picking out the right electric linear actuators to suit your needs, feel free to reach out to us! We are experts in what we do and will be happy to help with any questions you may have!

sales@progressiveautomations.com | 1-800-676-6123