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.

CONVERSION METHOD

🔌 VOLTAGE

🔧 RESISTANCE

CURRENT

15 A

MILLIAMPS

15,000 mA

METHOD

Ohm's Law

FORMULA

I = V / R

Volts to Amps using Resistance — Reference Table

Voltage	4 Ω	8 Ω	12 Ω	16 Ω
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

💡 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).

Method 2: Using Power (Watt's Law)

I = P / V (DC)
I = P / (V × 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 — 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 — Allowable Ampacities of Insulated Conductors
NFPA 70 — National Electrical Code (NEC), 2023 Edition

1,440 watts ÷ 120 volts = 12 amps — exactly 80% of a 15-amp breaker, the NEC-recommended maximum for continuous loads.