Lever Calculator
Work out a lever’s mechanical advantage and the effort force needed to lift a load, from the effort and load arm lengths measured from the fulcrum.
Lever result
The physics behind the lever
A lever is a rigid bar that pivots on a fixed point called the fulcrum. In equilibrium, the turning effect (moment) of the effort force must equal the turning effect of the load: effort force × effort arm length = load force × load arm length. Rearranging that gives the effort force you need for any load, once you know both arm lengths.
The ratio of the two arm lengths — effort arm ÷ load arm — is the lever’s mechanical advantage. A crowbar with a long handle and a short business end has a high mechanical advantage, letting you move a heavy object with modest force. A pair of tweezers has the arms reversed, trading force for the fine control and speed you need to pick up something small.
Frequently Asked Questions
What is mechanical advantage on a lever?
Mechanical advantage (MA) is the ratio of the effort arm length to the load arm length, measured from the fulcrum. An MA greater than 1 means the lever multiplies your force — you push with less force than the load weighs. An MA less than 1 does the opposite: it trades force for extra speed or distance at the load end, as in a fishing rod or a broom.
Does the class of lever (1st, 2nd, or 3rd) change the formula?
No. The formula — effort force × effort arm = load force × load arm — is the same moment balance regardless of where the fulcrum, load, and effort sit relative to each other. The lever's class only describes their arrangement; the mechanical advantage is still just the ratio of the two arm lengths.
Why does a longer effort arm make lifting easier?
A longer effort arm means you sweep through a bigger circular distance for the same small movement at the load end. Work (force × distance) is conserved in an ideal lever, so trading distance for force lets you lift a heavy load with a smaller push — the classic 'give me a lever long enough' idea.
Does this calculator account for friction at the fulcrum?
No — this is the ideal, frictionless mechanical-advantage calculation taught in an introductory physics course. A real fulcrum (a hinge, a pivot pin) has some friction, so the effort force needed in practice will be slightly higher than the ideal figure shown here.
Educational estimate only, based on ideal (frictionless) lever mechanics. Verify load-bearing or safety-critical figures with a qualified engineer.