What is the formula for amps to volts?

There are two common formulas. Ohm's Law: V = I × R, where I is current in amps and R is resistance in ohms. Power formula: V = P / I, where P is power in watts and I is current in amps.

Can I use this for AC circuits?

Yes for resistive loads. For reactive AC circuits (inductors, capacitors) the same formula applies to RMS values, but impedance replaces resistance. This calculator works correctly for pure resistive loads.

What if my current value is zero?

Division by zero is undefined in the P / I formula — the calculator will show an error if you enter 0 amps. In practice, zero current means no voltage drop across a load.

How accurate are the results?

Results are computed with full floating-point precision and rounded to 4 significant figures for display. They are as accurate as the input values you provide.

What units does this calculator use?

Inputs are in standard SI units: amps (A) for current, ohms (Ω) for resistance, and watts (W) for power. The result is in volts (V).

Amps to Volts Calculator

Name: Amps to Volts Calculator
Availability: InStock
Author: Nham Vu

Enter current plus either resistance or power to calculate voltage using Ohm's Law.

Formula

Current (I)

Resistance (R)

Enter current and resistance or power to calculate voltage.

Ohm's Law Reference

Find	Formula	Example
Voltage (V)	V = I × R	2 A × 10 Ω = 20 V
Voltage (V)	V = P ÷ I	60 W ÷ 3 A = 20 V
Current (I)	I = V ÷ R	20 V ÷ 10 Ω = 2 A
Resistance (R)	R = V ÷ I	20 V ÷ 2 A = 10 Ω

Copied!

Summary

Enter current plus either resistance or power to calculate voltage using Ohm's Law.

How it works

Choose a formula: Ohm's Law (V = I × R) or Power (V = P / I).
Enter the current value in amps (A).
Enter either resistance in ohms (Ω) or power in watts (W) depending on your formula.
Voltage is calculated instantly as you type.
Use the Reset button to clear all fields and start over.

Use cases

Verify voltage across a resistor in a circuit design.
Size a power supply when current and load resistance are known.
Troubleshoot automotive or home wiring faults.
Check motor voltage from measured current and rated power.
Teach or study basic Ohm's Law relationships.
Cross-check measurements from a multimeter reading.

Frequently Asked Questions

Last updated: 2026-06-10 · Reviewed by Nham Vu