Electric Field of a Point Charge Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 10/10/2026
The electric field created by a point charge is calculated with E = k × Q ÷ r², where k is the Coulomb constant (about 8.99 × 10⁹ N·m²/C²), Q the charge, and r the distance to the point considered. A charge of 1 µC creates, at a distance of 1 m, an electric field of about 8,987.5 N/C.
Explanation
The electric field describes the influence a charge exerts on the space around it, independently of any other charge: it is a property of space at every point, which exists even if no second charge is present to "feel" it. This formula is directly related to our Coulomb's law calculator, which calculates the force between two charges: in fact, the force felt by a second charge q placed in this field is simply F = q × E, which gives exactly F = k × Q × q ÷ r² once substituted — Coulomb's law is therefore nothing other than the force exerted on a test charge placed in the field created by another charge. The electric field decreases with the square of the distance, exactly like the Coulomb force or gravitational strength: at twice the distance, the field is four times weaker. Its direction always points radially from the charge that creates it: away from it if the charge is positive, or toward it if the charge is negative — this calculator gives only the magnitude (the norm) of this field, not its full vector direction.
Example: a 2 µC charge, at 0.5 m
Inputs
Charge: 2 µC. Distance: 0.5 m.
Calculation
E = 8.9875 × 10⁹ × (2 × 10⁻⁶) ÷ 0.5² = 8.9875 × 10⁹ × 2 × 10⁻⁶ ÷ 0.25 = 71,900 N/C.
Result
The electric field created by this charge at 0.5 m is 71,900 N/C.
Frequently asked questions
What is the difference between the electric field and the electrostatic force?
The electric field is a property of space created by a single charge, which exists independently of any other charge present. The electrostatic force, on the other hand, only occurs between two charges: it is calculated by multiplying the field created by the first charge by the value of the second charge, F = q × E — this is exactly what our Coulomb's law calculator does, combining the two charges directly.
Why does the electric field decrease with the square of the distance?
This inverse-square decrease reflects the fact that a charge's electric influence spreads over the surface of an imaginary sphere centered on it, whose area itself grows with the square of the radius (4πr²): as you move away, the same "amount" of electric field is diluted over an ever-larger surface, hence this inverse quadratic dependence — the same geometric logic that explains the law of universal gravitation.
What happens if the charge Q is negative?
The calculation stays the same, and the result itself becomes negative: this sign carries information about the field's direction, under the convention where a positive field points away from the charge. A negative charge thus produces an electric field oriented toward it (surrounding positive charges would be attracted to it), while a positive charge produces a field oriented away from it — exactly the same sign convention as for the force in our Coulomb's law calculator.