Case 1
- Load
- 100N
- Load arm
- 0.5m
- Effort arm
- 2m
25.00N
Open with these valuesLever Calculator
25.00N
Result: 25.00 NA lever balances when load × load arm equals effort × effort arm, so the effort you need is (load × load arm) ÷ effort arm. Both distances are measured from the pivot, not from each other. Doubling the effort arm halves the force you have to apply.
Worked examples
Case 2
- Load
- 200N
- Load arm
- 0.1m
- Effort arm
- 1m
20.00N
Open with these valuesCase 3
- Load
- 600N
- Load arm
- 0.4m
- Effort arm
- 1.2m
200.00N
Open with these valuesHow it's calculated
effort = (load × load arm) ÷ effort arm
- StepEnter the load you want to move, in newtons.
- StepMeasure the load arm: pivot to the point where the load sits.
- StepMeasure the effort arm: pivot to the point where you push.
- ResultRead the force you need at the effort arm.
Reference table
| Load, load arm, effort arm | Example | Effort |
|---|---|---|
| 10, 0, 2 | Load sits on the pivot | 0 |
| 200, 0.1, 1 | Crowbar | 20 |
| 1000, 0.05, 2 | Long pry bar | 25 |
| 100, 0.5, 2 | Two-to-one lever | 25 |
| 50, 1, 1 | Balanced seesaw | 50 |
| 300, 1.5, 2.5 | Seesaw, off-centre | 180 |
| 600, 0.4, 1.2 | Wheelbarrow | 200 |
Questions
How do I calculate the force needed on a lever?
Use the law of the lever: effort = (load × load arm) ÷ effort arm. Multiply the load by the load arm to get the load moment, then divide by the effort arm. A 100 N load on a 0.5 m arm, pushed from a 2 m effort arm, needs (100 × 0.5) ÷ 2 = 25 N.
What is the law of the lever?
A lever balances when the load times its distance from the pivot equals the effort times its distance: load × load arm = effort × effort arm. Because each force is multiplied by its arm, a longer arm lets a smaller force balance a larger one.
Why does a longer lever make the work easier?
Because the effort is divided by the effort arm. A longer effort arm means the same load needs less force — the principle behind crowbars, wheelbarrows and seesaws, trading a longer push for a smaller one.
What about the mechanical advantage?
That is the effort arm divided by the load arm, and it says how many times the lever multiplies your force. An advantage of 4 means you apply a quarter of the load, which is exactly what the effort figure above already shows you.
Which units should I use?
Newtons for the load and metres for both arms, which gives the effort in newtons. To turn a mass into a force, multiply the kilograms by 9.81 — a 10 kg mass weighs about 98 N. Any consistent pair of units works, because the arms cancel.
Sources and last check
Information, not professional advice.