Physics

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Coulomb's Law Calculator.

Calculate electrostatic force magnitude between two point charges.

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01

Set your values

Results update as you type.

force: 1.79751 N

force

0.000000N

Results update automatically as you type.

This page applies only the stated idealized equation and explicit inputs; verify specialized engineering, medical, or safety decisions against applicable standards.

Use Cases

Physics Homework and Exam Prep

Quickly verify your manual calculations for electrostatic force problems in introductory physics courses.

Example: Check the force between a +2 µC and a -3 µC charge separated by 0.05 m.

Engineering Design and Prototyping

Estimate the electrostatic force between charged components in MEMS devices or electrostatic actuators.

Example: Estimate the force between two charged plates in a micro-switch.

Frequently Asked Questions

What is Coulomb's Law?
Coulomb's Law states that the electrostatic force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. The calculator uses this law to compute the force magnitude.
What units should I use for the charges and distance?
Enter the first and second charges in coulombs (C) and the separation distance in meters (m). The calculator will output the force in newtons (N).
Does the calculator account for the direction of the force?
No, this calculator only computes the magnitude of the electrostatic force. The direction depends on the signs of the charges: like charges repel, opposite charges attract.

Tips & Common Mistakes

Tips

  • Ensure charges are in coulombs (C). If you have microcoulombs (µC), convert by multiplying by 10^-6.
  • Distance must be in meters (m). Convert from centimeters or millimeters by dividing by 100 or 1000 respectively.
  • The calculator gives the force magnitude; remember that like charges repel and opposite charges attract.
  • For very small distances, the force can be extremely large, so double-check your inputs for accuracy.

Common Mistakes to Avoid

  • Forgetting to convert charges from microcoulombs or nanocoulombs to coulombs before entering them.
  • Using distance in centimeters or millimeters without converting to meters, leading to incorrect force values.
  • Confusing the sign of the force: the calculator returns magnitude only, so you must determine direction separately.

Last updated: August 13, 2026