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Coulomb's Law Calculator

Find the electric force between two charges — and whether they attract or repel.

  • Free
  • No sign-up
  • Nothing is sent or stored
C
C
m

Result

Electrostatic force
-21.5701 N
Charge 1 (q₁)
2 × 10^-6 C
Charge 2 (q₂)
-3 × 10^-6 C
Distance (r)
0.05 m
Direction
Attractive (opposite charges)
How it was calculated
  1. F = k × q₁ × q₂ ÷ r²
  2. k = 8.9875517923 × 10⁹ N·m²/C²
  3. F = -21.570124 N
Enter charges with their signs. 1 µC = 1 × 10⁻⁶ C (type 1e-6).

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved.

How to use the Coulomb's Law Calculator

  1. Pick what to solve for.
  2. Enter the charges in coulombs (with signs) and the distance in metres.
  3. Read the force and its direction.

What does this tool do?

Coulomb's law is the electrical counterpart of gravity: the force is proportional to the product of the charges and falls with the square of the distance.

Opposite charges attract (negative force) and like charges repel (positive force). Use scientific notation for small charges: 1 µC is 1e-6 C.

Why use it?

  • Solve for force, charge or distance.
  • Attract/repel direction.
  • Scientific notation input.

The formula

F = k q₁ q₂ ÷ r²
k = 8.988 × 10⁹ N·m²/C²

Privacy

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved. There's no account to create and nothing to install.

Last reviewed by the M2Toolkit team.

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