Volts to Amps Calculator
Find current from either power (A = P ÷ V) or resistance (A = V ÷ R).
How do you convert volts to amps?
You need one more quantity — power or resistance. If you know power, divide watts by volts: A = P ÷ V. A 60 W bulb on 120 V draws 60 ÷ 120 = 0.5 A. If you know resistance, use Ohm's law: A = V ÷ R, so 12 V across 4 Ω gives 12 ÷ 4 = 3 A. Voltage alone is never enough.
Volts to Amps Formulas
When you know the power a device consumes, current is power divided by voltage. Example: a 600 W tool on 120 V draws 600 ÷ 120 = 5 A.
On AC, divide by the power factor as well. A 1,000 W motor at 230 V with PF 0.9 draws 1,000 ÷ (230 × 0.9) = 4.83 A.
For a purely resistive load, current is voltage divided by resistance. Example: 24 V across 8 Ω gives 24 ÷ 8 = 3 A. This is the classic form of Ohm's Law.
Volts to Amps from Power (A = P ÷ V)
| Power | at 12 V | at 120 V | at 240 V |
|---|---|---|---|
| 60 W | 5.000 A | 0.500 A | 0.250 A |
| 100 W | 8.333 A | 0.833 A | 0.417 A |
| 500 W | 41.67 A | 4.167 A | 2.083 A |
| 1000 W | 83.33 A | 8.333 A | 4.167 A |
| 1500 W | 125.0 A | 12.50 A | 6.250 A |
Frequently Asked Questions
Can I convert volts to amps with only voltage?
No. Voltage alone does not set the current — it depends on the load. You also need either the power (watts) or the resistance (ohms). With power: A = P ÷ V. With resistance: A = V ÷ R.
What is the formula for volts to amps?
It depends on what else you know:
- From power (DC):
A = P ÷ V - From power (AC):
A = P ÷ (V × PF) - From resistance:
A = V ÷ R
How many amps is 120 volts?
On its own, 120 V is not a number of amps — the current depends on the load. A 60 W bulb on 120 V draws 0.5 A; a 1,500 W heater on 120 V draws 12.5 A. Enter the wattage above to get an exact answer.
How do I use Ohm's Law to find amps?
Divide voltage by resistance: A = V ÷ R. For example, 12 V across a 4 Ω load gives 12 ÷ 4 = 3 A. See Ohm's Law explained for the full V–I–R relationship.