Coulomb's Law Calculator

How it works

Coulomb's law gives the electrostatic force between two point charges: F = k·q₁·q₂/r², with k ≈ 8.99 × 10⁹ N·m²/C². Enter charges in microcoulombs (µC) and a separation in metres, and the result comes out in newtons. The structure mirrors Newton's law of gravitation exactly — a product of two source quantities over the square of the distance. The difference is strength and sign: the electrostatic force is astronomically stronger, and it both attracts (opposite charges) and repels (like charges), while gravity only ever pulls. The inverse square is the dominant behaviour: double the separation and the force falls to a quarter; triple it and only a ninth remains. This law explains why atoms hold together, why a balloon rubbed on hair sticks to a wall, and why lightning needs an enormous charge to jump an air gap.