Which formula should I use?

Use Ohm's Law (I = V / R) when you know the resistance of the load. Use the power formula (I = P / V) when you know the power consumption (wattage) and supply voltage instead.

Does this work for AC circuits?

For purely resistive AC loads both formulas apply directly. For reactive loads (inductors or capacitors) you would need impedance in place of resistance, but the arithmetic is identical.

What units should I enter?

Voltage in volts (V), resistance in ohms (Ω), and power in watts (W). The result is always in amperes (A).

Why does the result show "—" instead of a number?

A result cannot be computed if any required input is zero, empty, or non-numeric. Fill in both fields with positive numbers to see a result.

How do I convert the result to milliamps?

Multiply the amperage result by 1000. For example, a calculated output of 0.5 A equals 500 mA. To convert milliamps back to amps, divide by 1000.

Volts to Amps Calculator

Convert volts to amps using Ohm's Law (I = V / R) or the power formula (I = P / V).

Formula

Voltage (V)

Resistance (R)

Ω

Enter values on the left to calculate current

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Summary

Quickly convert voltage (volts) to electric current (amps) using either Ohm's Law when resistance is known, or the power formula when wattage is known. Supports both DC and AC resistive circuit calculations with an instant, client-side result.

How it works

Select the formula you want to use.
For Ohm's Law, enter voltage in volts and resistance in ohms; current is calculated as I = V / R.
For the power formula, enter power in watts and voltage in volts; current is calculated as I = P / V.
Results update instantly as you type.
Click Copy Result to copy the computed amperage to your clipboard.

Use cases

Determine how many amps a device draws given its supply voltage and resistance.
Calculate current consumption of an appliance from its wattage and supply voltage.
Size fuses and circuit breakers correctly for a given load.
Verify wire gauge requirements based on expected current draw.
Check electrical specifications on datasheets and product manuals.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu

Volts to Amps Calculator

Use the Volts to Amps Calculator

Summary

How it works

Use cases

Frequently Asked Questions