Electrical & Lighting · Conversion · Free

Volts to Amps Calculator

Convert voltage in volts (V) to current in amps (A). Select the calculation type — volts to amps with watts or volts to amps with ohms — enter the volts plus watts or ohms, and press Calculate to get amps. Everything runs locally in your browser.

STEP 1

Choose the calculation type

Pick "volts to amps with watts" when you know the power in watts, or "volts to amps with ohms" when you know the resistance in ohms. The second input switches to match.

STEP 2

Enter volts and watts or ohms

Type the voltage in volts, then the power in watts (watts mode) or the resistance in ohms (ohms mode). Values must be zero or higher; the divisor — volts in watts mode, ohms in ohms mode — must be above zero.

STEP 3

Press Calculate, read amps

The result appears in amps (A), rounded to at most three decimals. Copy the result to your clipboard, or press Reset to clear everything and start over.

Volts to amps calculation

How do you convert volts to amps with watts?: The current I in amps (A) is equal to the power P in watts (W), divided by the voltage V in volts (V): I(A) = P(W) / V(V). For example, a 60 W load on a 12 V supply draws 60 / 12 = 5 A.
How do you convert volts to amps with ohms (Ohm's law)?: The current I in amps (A) is equal to the voltage V in volts (V), divided by the resistance R in ohms (Ω): I(A) = V(V) / R(Ω). For example, 120 V across a 40 Ω resistor pushes 120 / 40 = 3 A through it.
Why does the calculator reject zero volts (or zero ohms)?: Each mode divides by one of your inputs: watts mode divides by the voltage, and ohms mode divides by the resistance. Division by zero is undefined, so the calculator shows an error instead of a made-up number. A zero dividend is fine — 0 W at any voltage, or 0 V across any resistor, simply gives 0 A.
Which formula should I use?: Use the watts formula when you know how much power the load consumes, and the ohms formula when you know the load's resistance. They are consistent: combining P = V × I with I = V / R gives P = V² / R.
Worked example: A 1000 W heater on a 230 V mains supply draws I = 1000 W / 230 V ≈ 4.348 A. The same heater's hot resistance checks out with Ohm's law: R = V / I = 230 V / 4.348 A ≈ 52.9 Ω.

Privacy: every calculation runs in your browser tab — no value you type is sent anywhere. Copy result uses your clipboard only. Values are ideal DC / single-phase resistive results; verify real installations with a multimeter.