Murphy Bed Hardware Calculator

Calculate gas piston force, stroke length, and hardware requirements for a Murphy wall bed based on mattress weight and bed dimensions.

Mattress weight (lbs)

Bed frame / platform weight (lbs)

Bed length (in)

Bed width (in)

Number of gas pistons

Piston mount from pivot (in)

Lift assist factor (%)

Tab to move between fields

Required force per piston (lbs)

269.5

Total torque at pivot (lb-in)3,750

Piston stroke length (in)41

Piston extended length (in)70

Total bed weight (lbs)100

Estimated hardware cost ($)$150.00

Wall load with safety factor (lbs)150

Minimum stud anchors needed2

Size ClassFull

How to Use This Calculator

Enter Mattress Weight and Bed Frame/Platform Weight in pounds for the total folding load.
Enter Bed Length and Bed Width in inches and the Number of Gas Pistons.
Enter the Piston Mount Distance from the pivot and your desired Lift Assist Factor percentage.
Review Required Force Per Piston in pounds to select appropriately rated gas struts.
Check Minimum Stud Anchors and Wall Load with safety factor to ensure safe wall mounting.

How the result changes with Piston mount from pivot (in)

Piston mount from pivot (in)	Required force per piston (lbs)
5.4	399.3
8.9	242.3
13	165.9
17	126.8

Mattress weight (lbs): Weight of the mattress alone. Memory foam ~60-90 lbs, innerspring ~50-70 lbs.
Bed frame / platform weight (lbs): Weight of the plywood platform and face panel that fold with the mattress.
Bed length (in): Mattress length in inches. Standard is 75", XL/King is 80".
Bed width (in): Mattress width: Twin 39", Full 54", Queen 60", King 76".
Number of gas pistons: Most Murphy beds use 2 pistons. Heavy beds may need 4.
Piston mount from pivot (in): Distance from the wall pivot point to where the piston attaches. Farther = less force needed per piston.
Lift assist factor (%): Extra force above balance so the bed lifts easily. 10-20% is typical.

Required force per piston (lbs): Each gas piston must provide this much force when extended.
Total torque at pivot (lb-in): The rotational force the pistons must overcome.
Piston stroke length (in): Recommended gas strut stroke length.
Piston extended length (in): Total piston length when fully extended.
Total bed weight (lbs): Combined mattress + frame weight.
Estimated hardware cost ($): Approximate cost for pistons, mounting brackets, and piano hinge.
Wall load with safety factor (lbs): Dynamic load the wall anchoring must support (1.5x safety factor).
Minimum stud anchors needed: Number of wall studs to lag-bolt into for safe mounting.

Identify Input Parameters
4 parameters
Mattress weight (lbs) = 60, Bed frame / platform weight (lbs) = 40, Bed length (in) = 75, Bed width (in) = 54 = 7 input(s) provided
Calculate Required force per piston
Required force per piston = balanceForcePerPiston * assistMultiplier
269.5 = 269.5
Calculate Total torque at pivot
Total torque at pivot = totalWeight * cgDistance
3750 = 3750
Calculate Piston stroke length
Piston stroke length
41 = 41