Physics

Instant, private, and free

Electric Field of a Point Charge Calculator.

Calculate point-charge electric-field magnitude and potential in SI units.

On-device calculationNo signup
01

Set your values

Results update as you type.

Field magnitude: 898.755179 N/C

Field magnitude

898.755179N/C
Electric potential: 89.875518 V

Electric potential

89.875518V

Results update automatically as you type.

Use Cases

Physics homework and exam prep

Quickly verify your manual calculations for electric field and potential of a point charge, helping you check your work and understand the relationship between charge, distance, and field strength.

Example: Check the field 0.5 m from a 2 µC charge.

Electrostatics design and analysis

Engineers and technicians can estimate the electric field and potential near a charged sphere or point-like source to assess safety or design considerations.

Example: Estimate the field at 1 m from a 10 nC charge.

Frequently Asked Questions

What does this calculator compute?
This calculator computes the electric field magnitude (E) and electric potential (V) at a specified distance from a point charge. You input the charge in coulombs (C) and the distance in meters (m), and it uses the standard formulas E = kQ/r² and V = kQ/r, where k is Coulomb's constant.
What units are used for the inputs and outputs?
The inputs are the point charge in coulombs (C) and the distance from the charge in meters (m). The outputs are the electric field magnitude in newtons per coulomb (N/C) or volts per meter (V/m), and the electric potential in volts (V). All values are in SI units.
Can I use this for negative charges?
Yes, you can enter a negative charge value. The calculator will compute the magnitude of the electric field (always positive) and the electric potential, which will be negative for a negative charge. The direction of the field is not given, but the magnitude is correct.

Tips & Common Mistakes

Tips

  • Enter the charge in coulombs (C). For microcoulombs (µC), multiply by 1e-6; for nanocoulombs (nC), multiply by 1e-9.
  • Enter the distance in meters (m). Convert from centimeters (cm) by dividing by 100, or from millimeters (mm) by dividing by 1000.
  • Remember that the electric field magnitude is always positive, but the potential can be negative for negative charges.
  • The calculator assumes the charge is a point charge in a vacuum. For other media, the permittivity changes, which would affect the results.

Common Mistakes to Avoid

  • Forgetting to convert charge units to coulombs. For example, entering 5 µC as 5 instead of 5e-6 will give a result that is 10^12 times too large.
  • Forgetting to convert distance to meters. Using centimeters directly will give an incorrect field magnitude because the distance is squared in the formula.
  • Confusing electric field and electric potential. The field is a vector (magnitude here) and decreases with the square of the distance, while potential decreases linearly with distance.

Last updated: August 13, 2026