Calculators
Electric Potential Calculator
Calculate point-charge electric potential from charge and distance.
Electric Potential Calculator tool
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About This Tool
Electric potential tells you the electric potential energy per unit positive test charge at a location. For one isolated point charge, taking the potential at infinity as zero, the potential is V = kQ/r. Unlike electric field, potential is a scalar: it keeps the sign of the source charge but has no spatial direction. This calculator converts common charge and distance units and evaluates the ideal point-charge relationship locally in your browser.
How To Use It
- Enter the source charge, including its positive or negative sign, and choose the charge unit.
- Enter a distance greater than zero from the source charge and select the distance unit.
- Choose volts, kilovolts, or millivolts for the displayed result.
- Read the sign as part of the potential value. The result uses the standard reference V = 0 at infinity.
Examples
1 µC at 0.1 m
A +1 µC point charge at 0.1 m gives about +89,875.5 V using V = kQ/r.
Negative static charge
A -3 nC point charge at 5 cm gives about -539 V. The negative sign belongs to the scalar potential; it is not a direction.
Changing distance
For the same point charge, doubling the distance halves the potential magnitude because point-charge potential varies as 1/r, not 1/r².
Useful Notes
Electric potential formula
For an isolated point charge in vacuum, V = kQ/r, where Q is the signed source charge, r is the positive distance from it, and k is Coulomb's constant, approximately 8.9875517923 × 10^9 N·m²/C². The usual reference sets V = 0 infinitely far from the charge.
Potential is scalar
Electric potential has magnitude and sign but no vector direction. A positive source charge produces positive potential under the infinity-zero reference, while a negative source charge produces negative potential. Potentials from multiple point charges can therefore be combined algebraically when they use the same reference.
Potential versus electric field
For a point charge, potential varies as 1/r while electric-field magnitude varies as 1/r². Electric field is a vector measured in N/C or V/m; electric potential is a scalar measured in volts, where 1 V equals 1 J/C.
Why distance cannot be zero
The ideal point-charge expression divides by r and becomes singular at r = 0. A real charged object has finite structure, so the point-charge model is not a valid description of its interior at zero distance.
Assumptions and limitations
This calculator models one stationary ideal point charge in vacuum and uses zero potential at infinity. Multiple charges, continuous charge distributions, conductors, dielectric media, and other boundary conditions may require superposition, integration, or a different reference potential.
FAQ
What is the electric potential of a point charge?
Using zero potential at infinity, it is V = kQ/r. Keep the sign of Q because potential is signed even though distance is positive.
Is electric potential the same as electric field?
No. Potential is a scalar measured in volts and falls as 1/r for a point charge. Electric field is a vector measured in N/C or V/m and its magnitude falls as 1/r².
Can electric potential be negative?
Yes. With the standard zero-at-infinity reference, an isolated negative point charge produces negative electric potential.
What does one volt mean?
One volt is one joule per coulomb (1 V = 1 J/C), expressing electric potential energy per unit charge.