Murphy Bed Hardware Calculator

A Murphy bed is really a lever: it pivots at the wall, and the mattress-plus-frame weight acts like a load hanging off the far end that the gas pistons have to counterbalance so the whole thing can be lifted with one hand instead of wrestled into the wall. This calculator treats the bed's center of gravity as sitting at roughly half the bed's length from that pivot point, multiplies it by the combined mattress and frame weight to get the torque the pistons must overcome, then divides that torque by the piston mounting distance from the pivot and the number of pistons you're using to find the balancing force each piston needs to supply — mount the pistons farther from the pivot and each one needs less force, which is why placement matters as much as piston strength. On top of that pure balance point, a lift-assist percentage (10-20% is typical) is added so the bed doesn't just hang in equilibrium but actually swings up under its own power.

From there it recommends a piston stroke length and full extended length sized to the bed's dimensions, estimates hardware cost across pistons, mounting brackets, and a piano hinge, and — critically for safety — calculates the dynamic wall load with a 1.5x safety factor to recommend a minimum number of studs to anchor into, since a Murphy bed pulls on the wall every time it's lowered and raised. Keep in mind the center-of-gravity assumption (half the bed length) is a simplifying approximation, not a measurement of your actual construction, so treat the piston force estimate as a solid starting point for shopping gas struts rather than an exact spec — verify against the manufacturer's rated piston force and a load-bearing reference for anything near the edge of typical framing capacity.