Gas Spring Calculator
Find a first gas spring force for a hinged lid from its weight and arm lengths, then check the maker's size data before use.
Distance from the hinge to the lid's balance point.
Distance from the hinge to the spring's lower mount.
Result
30 lb
A 20lb lid with this geometry needs an estimated 30lb of gas spring force
Quick Answer
A gas spring calculator balances lid weight at the hinge. Force equals weight times the hinge-to-CG length, divided by the hinge-to-mount length. A 20 lb lid at 12 inches and an 8-inch mount gives 30 lb. Educational estimate only. This simple math leaves out angle, travel, and safety margin. Check the maker's tool for safety-critical mounts.
Gas Spring Force Estimate Explained For Hinged Panels
A gas spring calculator gives a first force check for a hinged lid, hatch, door, or panel. The math weighs the lid's turn about the hinge against the spring mount arm. More weight or a farther CG raises the result. A mount farther from the hinge lowers the result. Camloc uses the same moment rule in its gas spring guide. A real part needs more data. Mount angle, stroke, spring count, heat, rub, hinge strength, and force change through travel all matter. Bad mount points can make a lid rise or fall too fast. Use this number to start a maker check. Do not use the number alone to pick or fit a strut or to prove that the mount is safe.
The Lever-Arm Formula Behind Gas Spring Force Estimates
Safety Disclaimer: Educational estimate only. This simplified lever-arm calculation does not account for mounting angle, lid travel, or safety margin. Always verify gas spring selection against the manufacturer's sizing tool and spec sheet before use, especially for any safety-critical mounting.
- Estimated Force = (Lid Weight × Hinge-To-CG Distance) ÷ Hinge-To-Mount Distance.
Lid weight: the lid or panel weight in pounds.
Hinge-to-CG distance: the distance from the hinge to the center of gravity.
Hinge-to-mount distance: the simple spring mount distance from the hinge.
Estimated force: the ideal holding force in pounds-force.
Using This Gas Spring Calculator In Five Clear Steps
Inputs
- Lid or panel weight: enter the panel weight in pounds.
- Hinge to center of gravity: enter the center-of-gravity distance from the hinge.
- Hinge to spring mount: enter the spring mount distance from the hinge.
Steps
- Weigh the lid or use checked design data.
- Find the lid's center of gravity.
- Measure both distances in the same unit.
- Enter the three values.
- Read the estimate, then check the maker's sizing tool.
Gas Spring Force Example With Every Step Shown Clearly
Lid weight is 20 lb, hinge-to-CG distance is 12 in, and hinge-to-mount distance is 8 in.
- Calculate moment torque: 20 lb × 12 in = 240 lb-in.
- Divide torque by mount distance: 240 lb-in ÷ 8 in = 30 lb-force.
The simple force estimate is 30 lb-force. No rounding is needed.
When A Gas Spring Force Estimate Fits Hinged Lid Checks
Use the estimate for an early toolbox lid, truck cap, cabinet door, or prototype check. Use maker software and qualified review before any safety-critical use.
For nearby leverage and moment calculations, see the engineering calculators hub and search the glossary for common engineering terms.
Assumptions
- The formula models one simple spring.
- Weight acts at the entered center-of-gravity distance.
- Spring force acts through the entered mount distance.
- Both distances use the same unit.
- Rounding happens after the calculation.
Limitations
- Educational estimate only. This simplified lever-arm calculation does not account for mounting angle, lid travel, or safety margin. Always verify gas spring selection against the manufacturer's sizing tool and spec sheet before use, especially for any safety-critical mounting.
- The result does not model force change through the stroke.
- Heat, friction, hinge strength, and moving loads are not included.
In Practice
A common error is using the spring length as the mount distance. The force arm depends on the spring line at each lid angle. Check the mount points, then test the result in the maker's model.
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Frequently Asked Questions About Gas Spring Sizing
Does A Larger Mount Distance Reduce Required Force?
A longer useful mount arm lowers the shown force for the same lid load. The spring acts farther from the hinge. Angle and lid travel still matter, so arm length alone cannot set the part size.
Does This Calculator Size One Strut Or Two Struts?
The formula gives a one-strut result for the stated simple model. Two struts do not always mean two parts at half the shown force. Angle, load share, rub, and maker data still need review.
Why Must The Center Of Gravity Be Measured?
The CG length sets the lid's turning force around the hinge during use. Two lids with the same weight can need unlike support forces. Use a known CG instead of guessing the midpoint. A wrong CG can change the part choice.
Can This Estimate Replace A Maker Sizing Tool?
This force check cannot replace the manufacturer's tool or spec sheet for a real mount. Maker methods check stroke, angle, force change, heat, and other facts. High-risk lids also need an expert design and safety check before use.
Sources
Last updated: . Reviewed for accuracy against the formula shown above.