Lever Calculator
A lever is one of the six classical simple machines. It consists of a rigid bar that pivots around a fixed point called the fulcrum. By applying a small force at a large distance from the fulcrum, you can move a heavy load at a shorter distance. The principle of moments states that F₁ × d₁ = F₂ × d₂, and this calculator uses it to find the load force and mechanical advantage.
The lever principle, discovered by Archimedes (“Give me a place to stand, and I shall move the Earth”), states that torques must balance: F₁ × d₁ = F₂ × d₂. The mechanical advantage MA = d₁/d₂ tells you how much the lever multiplies your effort force. An MA of 4 means a 50 N effort can lift a 200 N load.
There are three classes of lever based on the relative positions of effort, fulcrum, and load. Class 1 (fulcrum between effort and load): seesaws, crowbars, scissors. Class 2 (load between fulcrum and effort): wheelbarrows, nutcrackers, bottle openers. Class 3 (effort between fulcrum and load): tweezers, fishing rods, the human forearm. Classes 1 and 2 can provide MA > 1; class 3 always has MA < 1 but multiplies speed and range of motion.
Like all simple machines, levers obey conservation of energy: what you gain in force, you lose in distance. The effort moves through a larger arc while the load moves through a smaller arc. This principle underlies countless tools, machines, and biological systems from ancient construction to modern robotics.