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How-to guide

How to Calculate Coulomb's Law: Formula, Steps & Examples

Learn how to calculate Coulomb's Law — the formula explained step by step, with worked examples and a free calculator to check your answer.

By Vikram Iyer, M.Sc Mathematics · Updated Jun 2026 · 2 min read

Calculating your electrostatic force is straightforward once you know the Coulomb's Law formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Coulomb's Law Calculator.

What is Coulomb's Law?

The Coulomb's Law calculation tells you your electrostatic force from a few simple inputs. The figure you are solving for here is the electrostatic force.

The Coulomb's Law formula

This calculation combines several inputs through a multi-step method rather than a single one-line formula. Enter the values below and the calculator resolves each step in order. The inputs it needs are:

  • Charge 1 — a value measured in C. Example: 0 C.
  • Charge 2 — a value measured in C. Example: 0 C.
  • Distance apart — a value measured in m. Example: 0.1 m.

How to calculate it step by step

  • Write down the charge 1 (for example, 0 C).
  • Write down the charge 2 (for example, 0 C).
  • Write down the distance apart (for example, 0.1 m).
  • Apply the formula above to get your electrostatic force.
  • Double-check the result with the Coulomb's Law Calculator.

Worked examples

Example 1

Input / OutputValue
Charge 10 C
Charge 20 C
Distance apart0.1 m
Electrostatic force0.898750

With charge 1 of 0 C, charge 2 of 0 C and distance apart of 0.1 m, the electrostatic force works out to 0.898750.

Example 2

With charge 1 of 0 C, charge 2 of 0 C and distance apart of 0.1 m, the electrostatic force works out to 1.797500.

ResultValue
Electrostatic force1.797500

Example 3

With charge 1 of 0 C, charge 2 of 0 C and distance apart of 0.1 m, the electrostatic force works out to 4.493750.

ResultValue
Electrostatic force4.493750

Tips for an accurate result

  • Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
  • Round only at the very end. Rounding inputs early can shift the final answer noticeably.
  • Re-run the numbers whenever an input changes, rather than estimating from an old result.

Prefer not to do the maths by hand? — the Coulomb's Law Calculator does it instantly, for free, with the formula and a worked example built in.

Continue exploring science calculators with these tools: Impulse Calculator, Elastic Potential Energy Calculator, Thermal Expansion Calculator, Buoyancy Force Calculator, RPM to Linear Speed Calculator.

Calculators in this guide

Frequently asked questions

Gather each input, apply the formula step by step keeping your units consistent, and round only at the end. You can verify your answer instantly with the Coulomb's Law Calculator.

It uses the standard formula with exact arithmetic, so the result is correct for the inputs you enter. Bear in mind that real-world outcomes can still differ when underlying assumptions change.

Vikram Iyer · M.Sc Mathematics

Vikram Iyer is a mathematics educator with over fifteen years of teaching experience, specialising in making quantitative concepts clear and practical for everyday use.