Electric Field of a Point Charge Calculator

Kaava

How this is calculated

A point charge q creates an electric field that points radially outward (for positive charge) or inward (for negative charge). The magnitude of that field at a distance r is given by Coulomb's law for fields: E = k·|q| / r², where k ≈ 8.9875×10⁹ N·m²/C² is Coulomb's constant. Enter the charge q in coulombs (C) and the distance r in meters (m); the result E is reported in newtons per coulomb (N/C), which is identical to volts per meter (V/m).

The calculation uses the absolute value of the charge for the field magnitude, since the sign only determines direction, not strength. Because the field depends on 1/r², it follows an inverse-square law: doubling the distance reduces the field to one quarter, while halving the distance multiplies it by four. The curve samples E at distances from 0.2r to 2r so you can see this rapid decay around your chosen point.

This model assumes an isolated point charge (or a spherically symmetric charge) in vacuum or air, with no nearby conductors or dielectrics that would distort the field. The distance must be greater than zero, because the field formally diverges at r = 0. The force on a test charge placed in the field is F = q_test·E, so the field equals the force experienced by a +1 C test charge.