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Lever Mechanical Advantage Calculator

Find a lever's mechanical advantage.

Result

3.0000
300.00 N

How it is calculated

For an ideal lever in balance, the turning effects about the pivot are equal. The tool computes MA = Le ÷ Ll and Fload = Fe × MA. Le is the effort arm (pivot to where you push) and Ll the load arm (pivot to the load), both in the same length unit, so MA has no unit. Fe is the effort force in newtons and the load force is shown in newtons. Both arms must be above zero and the effort cannot be negative. MA is shown to four decimals, the force to two. Friction and the lever's own weight are ignored.

Worked example

A crowbar has its pivot 0.5 m from the load and you push 1.5 m from the pivot with 100 N. The mechanical advantage is 1.5 ÷ 0.5 = 3.0000. The force at the load is 100 × 3 = 300.00 N. The price of this gain is distance: the load moves only one third as far as your hands do.

Try this example →

Common mistakes

  • Swapping the two arms. Dividing load arm by effort arm gives 0.33 instead of 3, the reverse of the true advantage.
  • Measuring arms from the end of the bar instead of from the pivot, which changes both lengths.
  • Using the plain arm length when the push is not perpendicular to the bar. The formula assumes force at right angles to the bar.
  • Mixing units for the two arms, such as centimetres for one and metres for the other.
  • Entering the effort in kilograms-force or pounds when the tool works in newtons. Multiply kg by about 9.81 first.

Sources

About this calculator

Mechanical advantage is the ratio MA = effort arm length / load arm length, following the lever principle that effort force × effort arm equals load force × load arm at balance. An MA greater than 1 means the lever multiplies input force at the cost of moving the effort a greater distance, while an MA below 1 trades force for speed and range of motion.

This relationship underlies everyday tools like crowbars, wheelbarrows and bottle openers, and engineers apply it when designing anything from door hinges to construction cranes. Biomechanists and physical therapists use the same lever math to analyze how joints and muscles generate force around the body — the forearm, for instance, acts as a third-class lever with the elbow as fulcrum — which is central to understanding both athletic performance and musculoskeletal injury.

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Comments (1)

  • Editorial team

    The tool gives the force at the load for an effort you choose. To go the other way, divide the weight you must move by the mechanical advantage. A 60 kg rock weighs about 589 N, so with an advantage of 3 you need roughly 196 N at the handle. Because friction and the bar's own weight are ignored, plan for a bit more in practice. What are you trying to lift, and with which lever?

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