North American circuits

120V Amps to Watts Calculator

Watts = Amps × 120V × PF

120V Amps to Watts Calculator

Designed for US outlets, small appliances, home circuits, and North American devices.

Live Result
Formula-backed — instant professional result
CALCULATED POWER
0 W
Also equals 0 kW
Formula used Watts = Amps × 120V × PF The primary result is shown in W using the formula displayed above. 10A × 120V × 1.0 = 1,200W

This calculator is an educational planning estimate. Verify safety-critical work with equipment nameplate data, local electrical code, and a qualified professional.

Convert 120V amps to watts for US household outlets. W = A × 120. Includes 15A, 20A, and 30A breaker planning limits.

AC amps to watts

Single-phase AC load path

Convert 120V amps to watts for US household outlets. W = A × 120. Includes 15A, 20A, and 30A breaker planning limits.

120V single-phase formula-first page-specific visual

120V Amps to Watts Calculator — US Household Circuits | Ampstowatt Guide

Single-phase AC path

Current, voltage, and power factor feeding a real watt result

AC pages need power factor context, so the visual connects outlet voltage, current draw, PF, and breaker planning.

Formula Watts = Amps x 120V x PF
120V Amps to Watts Calculator — US Household Circuits | Ampstowatt technical circuit diagram A premium electrical diagram showing the main values and conversion flow for 120V Amps to Watts Calculator — US Household Circuits | Ampstowatt. AC source 120 V 10 A PF 0.90 Load 1,080 W
120V Amps to Watts Calculator — US Household Circuits | Ampstowatt Single-phase AC path with real formula values and planning checkpoints.

Quick answer

Use this calculator to convert AC current into real watts with voltage and power factor.

Single-phase AC loads can be resistive or inductive. Resistive loads may be near PF 1.00, while motors, compressors, and HVAC equipment often need a lower power factor.

Watts = Amps x 120V x PF

Inputs to check before calculating

  • Use the correct nominal voltage for the circuit.
  • Enter measured current or nameplate running current.
  • Use realistic PF for motors, compressors, and transformer loads.
  • Compare the result with breaker and continuous-load limits.

Example: 10 amps at 120 volts

At 120 volts, 10 amps equals 1,200 watts before AC power-factor adjustments. Formula: 10 A x 120 V = 1,200 W.

Best use cases

  • 15A and 20A planning
  • Power factor support
  • Continuous-load guidance
  • single-phase AC load planning with clear unit labels.

Common mistake to avoid

Do not use DC-style amps x volts for every AC load when the equipment has a lower power factor.

How to use the result

Use the watt result for appliance planning, branch-circuit checks, and comparison with the main amps to watts formula.

Accuracy and safety note

Calculator output is a planning estimate. Final breaker sizing, wire gauge, derating, voltage-drop limits, equipment protection, and code compliance should be verified with manufacturer documentation and a qualified electrician or engineer.

For the broad formula, reference table, and breaker planning context, start with the main Amps to Watts Calculator.

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Start with the main conversion tool

Compare this voltage with the other common DC, household, mains, and industrial voltage calculators.Amps to Watts Calculator

Methodology, Review Notes, and Sources

How this calculator works

The calculator applies Watt's law for DC and resistive loads, then adds power factor for AC loads and the 1.732 multiplier for balanced three-phase line-to-line calculations.

  • DC and resistive loads: W = A x V
  • Single-phase AC: W = A x V x PF
  • Three-phase AC: W = 1.732 x A x V x PF

Editorial review

Last reviewed: June 26, 2026. Ampstowatt.com is built around the amps to watts conversion — our core specialty. Content is maintained by the Ampstowatt editorial team and checked for formula consistency, unit labels, calculator behavior, and safety wording.

The page is an educational planning reference, not a licensed electrical design or inspection service.

Reference sources

FAQ

120V Calculator FAQ

Fast answers before you use the calculator or compare formulas.

15A How many watts is 15 amps at 120V?

15 amps at 120V equals 1,800 watts (15 × 120 = 1,800). This is the maximum capacity of a standard 15A household circuit. For continuous loads, the NEC 80% rule limits you to 1,440 watts on this circuit.

20A How many watts is 20 amps at 120V?

20 amps at 120V equals 2,400 watts. Kitchen and bathroom outlets are typically on 20A circuits. The continuous load limit is 1,920 watts (80% of 2,400).

MAX What is the maximum wattage for a 120V outlet?

A standard 120V, 15A outlet can handle 1,800 watts maximum (15 × 120). A 120V, 20A outlet handles 2,400 watts. However, for devices running more than 3 hours continuously, stay below the 80% threshold: 1,440W on a 15A circuit, 1,920W on a 20A circuit.

240 Why do some appliances need 240V instead of 120V?

High-power appliances like dryers (5,500W), EV chargers (7,680W), and central AC (3,600W) need more watts than a 120V circuit can safely deliver. At 120V, a 5,500W dryer would draw 46 amps — far exceeding standard circuit limits. At 240V, it draws only 23 amps, which fits a 30A circuit safely.

PF Do I need power factor for 120V household calculations?

For most household loads (lights, heaters, toasters, hair dryers), power factor is 1.00 or very close, so the simple formula Watts = Amps × 120 is sufficient. Use power factor only for motor-driven appliances like refrigerators (PF 0.80–0.90), window AC units (PF 0.85), and large workshop tools.

OUT How many 120V outlets can I put on one circuit?

The NEC does not set a fixed number of outlets per circuit, but the total load must stay within the breaker rating. A 15A/120V circuit handles 1,800W max. Add up the wattage of everything plugged in. In practice, 8–10 general-purpose outlets on a 15A circuit is common when not all are loaded simultaneously.