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Physics formula

How to calculate force

Force measures how strongly a mass is pushed or pulled as its motion changes.

See the formulaOpen calculator
Direct answer
Formula
F = m * a

Use the table below to match each symbol with the right input. Keep units consistent before you start.

Force formula
Start here when you only need the equation and variable names.
Formula
F = m * a

Force measures how strongly a mass is pushed or pulled as its motion changes.

Variable meanings
Check each symbol, meaning, and unit before you calculate.
SymbolNameDescriptionUnit
FForcePush or pull on the object.N
mMassAmount of matter being accelerated.kg
aAccelerationChange in velocity per second.m/s^2
When to use this formula
Check that your situation matches the formula before you trust the result.
  • Start with it for Newton's second law problems where mass and acceleration are known.
Step-by-step method
Follow these steps when you are solving it by hand.
  1. 1Convert mass to kilograms.
  2. 2Convert acceleration to m/s^2.
  3. 3Multiply mass by acceleration.
  4. 4Report the answer in newtons.
Examples
These sample numbers show the order of operations and units.
Small cart
m
12 kg
a
3 m/s^2
  1. 1.F = 12 * 3
  2. 2.F = 36 N
Result
The force is 36 N.
Car acceleration
m
1,500 kg
a
2.5 m/s^2
  1. 1.F = 1500 * 2.5
  2. 2.F = 3750 N
Result
The force is 3,750 N.
Mistakes to avoid
Small input or unit errors can change the answer a lot.
  • Mixing metric and imperial units before solving the force formula.
  • Forgetting squared units such as m^2, m/s^2, or velocity squared.
  • Dropping negative signs when direction matters.
  • Rounding measured values too early in the calculation.
Open the Force Calculator
Open the calculator for the answer without rewriting the formula.

Enter your values in the related calculator, then compare the output with the hand method above.

Open Force Calculator
FAQs
Short answers for common formula questions.
Can I calculate Force by hand?

Yes. Write the units next to each value, convert rates or measurements first, and round only the final answer.

Why does my Force result differ from another calculator?

Most differences come from rounding, unit conversions, rate timing, or a slightly different version of the formula.

When is the Force Calculator better than hand math?

Open the Force Calculator to check several scenarios or skip the hand arithmetic.