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Lever Mechanical Advantage Calculator

Calculate a lever's mechanical advantage and the maximum load force it can balance, from the effort force and the effort/load arm lengths, in metric or imperial units.

Mechanical advantage
3×
Maximum load force balanced
150 N

How it works

A lever balances when the torque the effort force applies equals the torque the load applies about the fulcrum: effort force × effort arm = load force × load arm. Rearranging gives the maximum load force a given effort can lift or hold in balance, and the ratio of the two arms — effort arm ÷ load arm — is the lever's mechanical advantage: how many times the effort force gets multiplied.

A mechanical advantage greater than 1 (a long effort arm and a short load arm, like a crowbar prying up a nail) means a small effort force balances a much larger load. A mechanical advantage less than 1 (a pair of scissors' handle-to-blade-tip ratio, or tweezers) trades force for a bigger motion at the load end instead — the lever still balances the same torque equation, it just multiplies effort force down rather than up.

Both arm lengths only need to share a unit (both meters or both feet) for the ratio to come out correctly, and the resulting load force always lands in the same force unit the effort force was given in — no internal metric-to-imperial conversion is needed, the same scale-invariant reasoning this site's Hooke's law and simple pendulum calculators rely on.

FAQ

Does this account for the lever's own weight?

No — like the classic textbook treatment, this assumes a rigid, weightless (or at least torque-negligible) bar. A heavy plank or long steel bar would also contribute its own weight's torque about the fulcrum, which this calculator doesn't add in; for a lightweight lever (a crowbar, a wrench, a seesaw with people far outweighing the board) that's an excellent approximation.

What's a real-world example of each kind of lever this covers?

A wheelbarrow or a claw hammer pulling a nail both have the effort arm much longer than the load arm (mechanical advantage above 1 — easy to lift a heavy load). A pair of long-handled scissors cutting near the blade tip, or a fishing rod flicking a lure, have it the other way around (mechanical advantage below 1 — you trade force for reach or speed at the load end).

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