Gas Spring Calculator

A gas spring on a hinged panel is a moment problem about the hinge, not a force problem. Enter the panel weight, how far its centre of gravity sits from the hinge and the perpendicular distance from the hinge to the strut, and you get the force each strut has to produce; a second mode takes the two mounting points as coordinates and tracks the force, the moment arm and the strut length through the travel. The moment arm is the number that decides everything, and it is set entirely by where you drill. Picking a stronger strut does not fix mounting points in the wrong place.

Calculator Type
Units
Every weight and length box below is read in the pair you pick here, and every figure comes back in it.

The short version. You need the weight, how far the centre of gravity sits from the hinge, and the perpendicular distance from the hinge to the strut.

Measured along the panel. For a panel of even thickness it is half the length.
The perpendicular distance from the hinge pin to the line joining the two strut mounts. Not the strut length.
Zero is horizontal, which is the worst case for the weight.
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Units
Every weight and length box below is read in the pair you pick here, and every figure comes back in it.

Put the hinge at the origin. Give where each end of the strut bolts on, and this works out the moment arm, the force and the strut length at every point of the swing.

Zero for a flat lid. Negative for a hatch that slopes down away from the hinge.
Positive on the side the panel opens towards. Usually small or zero.
Positive in the direction the closed panel runs.
Positive is above the hinge. A lower mount usually means a bigger moment arm.
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