Lever Calculator
Find the mechanical advantage of a lever and the effort needed to lift a load from the effort arm and load arm lengths.
How much a lever multiplies your push, and what it takes to lift the load.
How the lever calculator works
A lever balances when effort × effort arm equals load × load arm (equal moments about the pivot). The mechanical advantage is effort arm ÷ load arm, and the effort needed is the load divided by it. A 2 m crowbar with the fulcrum 0.2 m from the load gives an advantage of 9: 500 N of load needs 56 N of push.
What you gain in force you pay in distance — the effort end moves nine times further than the load. The class of lever changes where the pivot sits, not the arithmetic.
Formula: MA = effort arm ÷ load arm · effort = load ÷ MA
Worked examples
| Inputs | Effort needed | Note |
|---|---|---|
| 500 N load, arms 1.5 m and 0.5 m | 166.67 N | MA 3 → 167 N |
| 500 N load, arms 1.8 m and 0.2 m | 55.56 N | a crowbar: MA 9 |
| 200 N wheelbarrow load, arms 1.2 m and 0.4 m | 66.67 N | a second-class lever |
FAQFrequently asked questions
What are the three classes of lever?
First: pivot between load and effort (seesaw, crowbar). Second: load between pivot and effort (wheelbarrow). Third: effort between pivot and load (tweezers, your forearm). The moment balance is the same for all.
Can a lever have a mechanical advantage below 1?
Yes — third-class levers do. They trade force for speed and range of motion, which is why arms and fishing rods are built that way.
Does the lever's own weight matter?
For a heavy bar, yes — its weight acts at its centre of mass and adds a moment. The calculator assumes a light lever.
Why is energy still conserved?
The effort moves further than the load by the same factor that it is smaller, so effort × distance equals load × distance. No free lunch, just a better grip on it.
Where these figures come from
- NIST — CODATA 2018 fundamental physical constants — G, g₀, R, c
- NIST Special Publication 811 — Guide for the use of the International System of Units — unit conversions
- The Engineering ToolBox — material properties — specific heats, expansion coefficients, densities
- National Measurement Institute — Australia's measurement authority
Last checked: September 2026. Constants are the CODATA 2018 values; formulas are the standard textbook forms.