Electrical

Amps to Watts Calculator

Convert electrical current in amps to real power in watts using circuit voltage, power factor, and DC, single-phase, or three-phase mode.

Enter load current and voltage. The calculator reports real watts using the selected circuit and power factor.

Calculation and worked example reviewed 2026-11-12. See our calculation methodology.

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Electrical

Enter your measurements

US UNITS

Load current

Voltage

Power factor

0–1

Circuit

Optional: Material Price ($ / unit)

YOUR ESTIMATE

1,920 W1.92 kW real power

2.4 kVA apparent power at 0.8 power factor.

Use line-to-line volts for balanced three phase.

Formula and example

How this calculation works

This estimator converts your entered jobsite inputs (load current, voltage, power factor, circuit) into consistent US trade units, computes the exact geometric baseline first, and then applies any selected waste or order allowance so you can verify both numbers before purchasing materials.

How does the amps to watts calculator formula work?

Real watts = volts × amps × power factor × phase multiplier; multiplier = 1 for DC/single phase or √3 for balanced three phase using line-to-line voltage.

(Amps to Watts Calculator)

where:

Load current – Entered in A (default reference: $10 A$ );
Voltage – Entered in V (default reference: $240 V$ );
Power factor – Entered in 0–1 (default reference: $0.8 0-1$ );
Circuit – Entered in selected option (default reference: $single$ );

The formula

Inputs to result

Real watts = volts × amps × power factor × phase multiplier; multiplier = 1 for DC/single phase or √3 for balanced three phase using line-to-line voltage.

Worked example

Check the math

A 10 A load at 240 V, single phase and power factor 0.8 uses 240 × 10 × 0.8 = 1,920 W of real power.

Quick lookup chart

Amps to Real Power (Watts) Reference by Circuit Type

Compares resistive unity power factor (PF = 1.0) against a typical inductive load (PF = 0.8).

Load Current	120V 1Φ (PF 1.0)	240V 1Φ (PF 1.0 / 0.8)	480V 3Φ (PF 0.8)
10 A	1,200 W	2,400 W / 1,920 W	6,651 W
15 A	1,800 W	3,600 W / 2,880 W	9,977 W
20 A	2,400 W	4,800 W / 3,840 W	13,302 W
30 A	3,600 W	7,200 W / 5,760 W	19,953 W

Limits and field checks

Before you use this result

The result is a steady-state electrical estimate. It is not an energy bill calculation, motor starting analysis or breaker recommendation.

Breaker trip rating (15 A, 20 A, 30 A) is not the actual operating current; measure running current with a clamp meter or read the nameplate.
Power factor reduces real watts delivered per amp of line current, meaning conductors carry full apparent current even when real wattage is lower.
Multi-wire 120/240 V residential circuits must be evaluated at the actual voltage feeding the specific appliance terminals.

Questions answered

Calculator FAQ

How many watts are 10 amps at 240 volts?+

At power factor 1 in single phase, 10 × 240 = 2,400 W. At power factor 0.8, real power is 1,920 W.

Is power factor the same as efficiency?+

No. Power factor relates real power to apparent power; efficiency relates useful output to input.