Science · Physics / Electrostatics

Coulomb’s Law Calculator

Enter two point charges and the distance between them to get the electrostatic force. Microcoulombs, nanocoulombs, millimetres and centimetres are all converted automatically.

F = k·q₁q₂/r²
q₁
Unit
q₂
Unit
r
Unit
Use a minus sign for negative charges. Equal signs → repulsion, opposite signs → attraction.
Electrostatic force
Magnitude · newtons—
🧑 Attraction 🧑 Repulsion
Coulomb’s law
F = k · |q₁q₂| / r²
k is the Coulomb constant, k ≈ 8.988 × 10⁹ N·m²/C². The force acts along the line joining the two charges: like charges repel and opposite charges attract. The formula only applies to point charges — for extended or conducting objects the real force depends on how charge is distributed.

⚡ Attract or repel

Signs are read automatically, so you always see whether the force pulls together or pushes apart.

➕ Charge units

Enter μC, nC or full coulombs — everything is converted to base SI units internally.

📏 Distance units

Work in mm, cm or m without converting anything yourself.

📈 Worked steps

See the substituted numbers and the exact multiplication chain, step by step.

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