Watt and Ampere Calculator
Electrical conversion tool

Watts to Amps Calculator

This Watts to Amps calculator — the free Watt and Ampere Calculator — converts electrical power in watts to current in amps using voltage and, for AC circuits, power factor and phase configuration. Switch direction to calculate watts from amps.

Quick answer: for DC, amps equal watts divided by volts. AC calculations also use power factor and, for balanced three-phase circuits, the square root of three.

  • Correct phase-aware formulas
  • Editable voltage
  • No universal conversion assumptions
Conversion direction
Electrical system
Quick voltage presets
Calculated result1000 W · 120 V · DC
8.333 A
Formula usedI = P / V

Custom voltage is always supported.

Published by Published Last updated Editorial process
01

What the calculation needs

01

Voltage Required

Watts cannot be converted to amps without voltage.

02

AC Power Factor

AC loads may require a power factor between 0 and 1.

03

Single and Three Phase

The selected electrical system determines the correct formula.

04

Instant Results

Results update as you change the electrical parameters.

DC / 1,000 W

See How Voltage Changes Current

For a fixed 1,000 W DC load, higher voltage means lower current.

Higher voltageLower current for the same power
12 V480 V
1,000 W / 120 V8.333 A
02
How It Works

How the Watt and Ampere Calculator Works – Step-by-Step Guide

1

Enter watts or amps.

2

Choose DC, single-phase AC, or three-phase AC.

3

Enter the circuit voltage.

4

For AC, add power factor and read the result.

The same calculator reverses the equation to determine watts from amps.

03
P / V / I

Formulas

Watts to Amps formula: DC uses I = P/V, single-phase AC uses power factor, three-phase AC uses sqrt(3)
W→A

Watts to Amps Formulas

DCDC circuit
I = P / V
I = AmpsP = WattsV = Volts
AC 1φSingle-phase AC real power
I = P / (V × PF)
PF = Power Factor
AC 3φBalanced three-phase AC using line-to-line voltage
I = P / (√3 × V × PF)
√3 ≈ 1.732
A→W

Amps to Watts Formulas

DCDC circuit
P = V × I
P = WattsV = VoltsI = Amps
AC 1φSingle-phase AC real power
P = V × I × PF
PF = Power Factor
AC 3φBalanced three-phase AC using line-to-line voltage
P = √3 × V × I × PF
√3 ≈ 1.732
04

Watts to Amps Examples

DC

1,200 W / 120 V

I = 1,200 / 120 = 10 A
AC 1φ

1,200 W / 120 V / PF 0.8

I = 1,200 / (120 × 0.8) = 12.5 A
AC 3φ

10,000 W / 400 V / PF 0.9

I = 16.0375 A
05
120 V DC

Watts to Amps Conversion Chart

These values use DC at the selected voltage. They are not universal watt-to-amp conversions.

Watts to Amps Conversion Chart
Watts (W)Volts (V)Amps (A)
101200.083333
251200.208333
501200.416667
1001200.833333
2001201.6667
5001204.1667
7501206.25
10001208.3333
150012012.5
200012016.6667
300012025
500012041.6667
06

Common Watts to Amps Conversions

100 W120 V DC0.833333 A
500 W120 V DC4.1667 A
1000 W120 V DC8.3333 A
1500 W120 V DC12.5 A
2000 W120 V DC16.6667 A
07

What Are Watts and Amps?

W

Watt (W)

Measures electrical power, or the rate of electrical energy transfer.

A

Ampere (A)

Measures electric current flowing through a circuit.

V

Volt (V)

Measures electrical potential difference and connects watts with amps.

Watts=Volts×Amps
08

Watts vs Amps: What Is the Difference?

QuantityUnitSymbolRepresents
PowerWattWRate of electrical energy transfer
CurrentAmpereAElectric current
VoltageVoltVElectrical potential difference
AC / DC

AC vs DC Watts to Amps

DC uses P = V x I. AC real-power calculations can also require power factor and phase configuration.

DC: I = P / V
1φ / 3φ

Single-Phase vs Three-Phase Current

For a balanced three-phase system using line-to-line voltage, the formula includes sqrt(3). Real installations can require additional engineering analysis.

3φ: P = √3 × V × I × PF

How Many Amps Is 1 Watt?

There is no universal answer because voltage is required. At 1 V DC it is 1 A; at 12 V it is about 0.0833 A; at 120 V it is about 0.00833 A.

How Many Watts Is 1 Amp?

Voltage is required. In DC, 1 A at 12 V is 12 W, at 120 V is 120 W, and at 230 V is 230 W.

How to Convert Watts to Amps Manually

  1. Identify the electrical system.
  2. Find the voltage.
  3. Find power factor for AC.
  4. Choose the matching formula.
  5. Calculate the current.

How to Convert Amps to Watts

Multiply current by voltage for DC. For AC, also multiply by power factor and, for balanced three-phase line voltage, by sqrt(3).

Switch to Amps to Watts
09

Why Voltage Changes the Amps

For the same power, increasing voltage reduces current in these DC examples.

1,200 W / 12 V100 A
1,200 W / 24 V50 A
1,200 W / 120 V10 A
1,200 W / 240 V5 A
PF

Why Power Factor Matters in AC Calculations

Power factor relates real power in watts to the voltage-current product. A lower power factor requires more current for the same real power.

10

Frequently Asked Questions

How do I convert watts to amps?

Choose the electrical system, enter watts and voltage, and add power factor for AC. The calculator applies the matching formula.

How many amps is 100 watts?

It depends on voltage and system. At 120 V DC, 100 W is about 0.8333 A.

How many amps is 1000 watts?

At 120 V DC, 1000 W is about 8.333 A. AC answers can differ because of power factor and phase.

Can I convert watts to amps without voltage?

No. Voltage is required to relate electrical power to current.

How many watts are in one amp?

There is no fixed value. In DC, watts equal volts multiplied by amps.

Does power factor affect amps?

Yes. For the same AC real power and voltage, a lower power factor produces a higher calculated current.

What power factor should I use?

Use the value supplied for the equipment or measured for the load. If unknown, do not assume every load has a power factor of 1.

What is the watts-to-amps formula for DC?

Amps equal watts divided by volts: I = P / V.

What is the formula for single-phase AC?

For real power, amps equal watts divided by volts times power factor: I = P / (V x PF).

What is the formula for three-phase AC?

For a balanced system using line-to-line voltage: I = P / (sqrt(3) x V x PF).

Why does higher voltage reduce current for the same watts?

Because current is power divided by voltage in DC and corresponding PF-adjusted AC formulas.

Are amps the same in AC and DC?

Not necessarily. AC calculations may include power factor and phase configuration.

What voltage should I enter?

Enter the voltage for the circuit or equipment. For this three-phase formula, use line-to-line voltage.

Can this calculator handle three-phase power?

Yes. It supports balanced three-phase real-power calculations using line-to-line voltage and power factor.

How to convert watts to ampsChoose the correct DC, single-phase, or three-phase formula.Watts, amps, and volts explainedUnderstand how electrical power, current, and voltage relate.Why power factor changes currentSee why lower power factor increases AC current.

Sources and further reading

The calculator formulas and definitions are presented alongside these independent measurement and electrical-engineering references.