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How does a lever increase force?

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A diagram displays six types of simple machines with labeled illustrations: inclined plane, wedge, screw, lever, wheel and axle, and pulley, each shown with real-world examples like ramps, axes, screws, seesaws, door handles, and pulleys lifting objects. — machine Six simple machines for transforming energy into work.

A lever increases force by utilizing the principle of mechanical advantage. This simple machine consists of a rigid bar that pivots on a support called a fulcrum.

The amount of force amplification is determined by the ratio of the distances from the fulcrum to the points where force is applied and where the load is moved. Specifically, if the distance from the fulcrum to the point of effort is greater than the distance from the fulcrum to the load, the force exerted at the load point will be proportionally greater than the force applied by the user.1

For example, if the effort arm is five times longer than the load arm, the lever will produce five times the input force. This relationship relies on the concept of torque, where the force is multiplied by the length of the lever arm to rotate the body around the fulcrum. In practice, the actual force output is slightly lower than the theoretical value due to mechanical efficiency losses caused by friction.123