Volts to Amps Calculator — I = P / V (Free)

Convert volts to amps from watts, or VA to amps (1- or 3-phase)

Operating Mode

Required Parameters

Voltage

Power

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Quick Answer

Amps = watts ÷ volts. 1,500 W at 120 V = 12.5 A. For VA: single-phase I = VA / V; three-phase I = VA / (√3 × VL).

Documentation

Volts to Amps Calculator

Convert volts to amps from watts (I = P / V) or from VA (single- or three-phase). Voltage alone is not enough — you must also know power or apparent power.

Quick start: 120 V and 1500 W → 12.5 A. For a nameplate in VA, switch to VA to Amps.

Volts to amps formula

I = P / V

Power	Voltage	Current
60 W	120 V	0.50 A
1,000 W	120 V	8.33 A
1,500 W	120 V	12.5 A
1,800 W	120 V	15 A
3,000 W	240 V	12.5 A

VA to amps

Single-phase: I = S / V
Three-phase: I = S / (√3 × VL)

Example: 5 kVA at 240 V single-phase is 20.8 A. The same 5 kVA at 208 V three-phase is 13.9 A.

Why “how many amps in a volt” has no answer

Amps and volts are different SI quantities. 1 V can push 1 A through 1 Ω, or 1 mA through 1 kΩ. Enter watts here, or use Ohm's law with resistance.

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Design Notes

You cannot convert volts to amps with voltage alone — power or resistance must be known. P = V × I is real power for DC and for AC at power factor 1. VA is apparent power; on three-phase systems line current uses √3. For resistive DC loads you can also use I = V / R or P = I²R.

Common Mistakes

1
Trying to convert volts to amps without watts, VA, or resistance — the units are not interchangeable by themselves.
2
Using P = V × I on a three-phase feeder without the √3 factor. Three-phase real power is √3 × VL × IL × PF.
3
Treating VA as watts when the load power factor is not 1. Watts = VA × PF.

Engineering Handbox

1. P = I × V 2. P = 10 × 120 = 1200 W

Verification10 A at 120 V is 1.2 kW. Reverse: I = 1200 / 120 = 10 A.

Knowledge Base

How do I convert volts to amps?

Divide power by voltage: I = P / V. Example: 1,200 W at 120 V = 10 A. Voltage alone is not enough — you also need watts, VA, or resistance.

How many amps is 1 volt?

There is no fixed answer. 1 V across 1 Ω is 1 A; 1 V into a 1 W load is 1 A; 1 V into 1 kΩ is 1 mA. Enter the power or use Ohm's law with resistance.

How do I convert VA to amps?

Switch to VA to Amps. Single-phase: I = VA / V. Three-phase: I = VA / (√3 × line voltage). 5,000 VA at 240 V single-phase is 20.83 A.

What is the difference between watts, VA, and amps?

Amps are current. Watts are real power (what does work and makes heat). VA is apparent power (volts × amps, before power factor). Watts = VA × PF. Breakers and wire are sized on amps; utility billing is usually on watts/kWh.

How do I convert volts to amps with resistance?

I = V / R (Ohm's law). 12 V across 4.7 Ω is 2.55 A. Use the Ohm's law calculator for that path; this page is the power-based converter.

What current does a 240 V, 3 kW heater draw?

I = 3,000 / 240 = 12.5 A. Same heater on 120 V would draw 25 A — that is why high-power loads use 240 V in North America.

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