Volts to Amps Calculator
Convert volts to amps using Ohm's Law (with resistance) or Watt's Law (with power). Calculate the current draw for any DC or AC electrical circuit.
V
Ξ©
CURRENT
15 A
MILLIAMPS
15,000 mA
METHOD
Ohm's Law
FORMULA
I = V / R
Volts to Amps using Resistance β Reference Table
| Voltage | 4 Ξ© | 8 Ξ© | 12 Ξ© | 16 Ξ© |
|---|---|---|---|---|
| 12 V | 3 A | 1.5 A | 1 A | 0.75 A |
| 24 V | 6 A | 3 A | 2 A | 1.5 A |
| 48 V | 12 A | 6 A | 4 A | 3 A |
| 120 V | 30 A | 15 A | 10 A | 7.5 A |
| 208 V | 52 A | 26 A | 17.33 A | 13 A |
| 240 V | 60 A | 30 A | 20 A | 15 A |
| 277 V | 69.25 A | 34.63 A | 23.08 A | 17.31 A |
| 480 V | 120 A | 60 A | 40 A | 30 A |
π‘ How to Convert Volts to Amps
Converting volts to amps tells you how much current flows through a circuit. This is critical for selecting the right wire size, fuse rating, and ensuring your circuit doesn't overheat.
Method 1: Using Resistance (Ohm's Law)
I = V / R
Where I is current (amps), V is voltage (volts), R is resistance (ohms).
Where I is current (amps), V is voltage (volts), R is resistance (ohms).
Method 2: Using Power (Watt's Law)
I = P / V (DC)
I = P / (V Γ PF) (AC)
Where I is current (amps), P is power (watts), V is voltage (volts), PF is power factor.
I = P / (V Γ PF) (AC)
Where I is current (amps), P is power (watts), V is voltage (volts), PF is power factor.
Example: Current Draw of a 120V Outlet
A 120V outlet powering a 1,440W load:
I = 1,440W / 120V = 12 amps
This is 80% of a 15-amp breaker β the NEC maximum for continuous loads.
I = 1,440W / 120V = 12 amps
This is 80% of a 15-amp breaker β the NEC maximum for continuous loads.
US Wire Sizing Based on Amperage
Knowing the current draw is essential for selecting the correct wire gauge per NEC Table 310.16:
| Current (Amps) | Min. Wire Gauge (AWG) | Typical Breaker |
|---|---|---|
| Up to 15A | 14 AWG | 15A |
| Up to 20A | 12 AWG | 20A |
| Up to 30A | 10 AWG | 30A |
| Up to 40A | 8 AWG | 40A |
| Up to 55A | 6 AWG | 50A or 60A |
References
- NEC Table 310.16 β Allowable Ampacities of Insulated Conductors
- NFPA 70 β National Electrical Code (NEC), 2023 Edition
1,440 watts Γ· 120 volts = 12 amps β exactly 80% of a 15-amp breaker, the NEC-recommended maximum for continuous loads.