Lever Calculator
Calculate the load a lever can balance using the law of the lever: effort × effort arm = load × load arm.
How it works
- 1Enter your effort force and the distance from the effort to the fulcrum (effort arm).
- 2Enter the distance from the load to the fulcrum (load arm).
- 3The calculator applies effort × effort arm = load × load arm to find the balanced load and mechanical advantage.
Use cases
- Designing crowbars, scissors, and seesaws where force multiplication is needed.
- Sizing wheelbarrows and hand trucks to find how much load a given handle force can lift.
- Teaching physics — visualising Class 1, 2, and 3 lever behaviour with live numbers.
Frequently asked questions
What is the law of the lever?
The law of the lever states that effort × effort arm = load × load arm. For example, 100 N applied 80 cm from the fulcrum balances 400 N placed 20 cm from the fulcrum, a mechanical advantage of 4.
What are the three classes of lever?
Class 1 has the fulcrum between effort and load (seesaw). Class 2 has the load between fulcrum and effort (wheelbarrow). Class 3 has the effort between fulcrum and load (tweezers). All obey the same moment equation.
How is mechanical advantage calculated for a lever?
Mechanical advantage = effort arm ÷ load arm. An MA greater than 1 means the lever multiplies your force; less than 1 trades force for greater movement speed or range.
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