# Watts to Amps Converter

Convert watts to amps with voltage and power factor. Free electrical converter for DC and AC circuits. Calculate current, VA, and BTU/hr from wattage.

## What this calculates

Convert electrical power in watts to current in amps for DC and single-phase AC circuits. Enter the wattage, voltage, and power factor to calculate the current draw, apparent power, and thermal output of any electrical device or circuit.

## Inputs

- **Power** (W) — min 0 — Enter the power in watts.
- **Voltage** (V) — min 0.001 — Enter the circuit voltage in volts.
- **Power Factor** — min 0.01, max 1 — Power factor for AC circuits (1.0 for DC or resistive loads, 0.8-0.95 typical for motors).

## Outputs

- **Current** (A) — Current in amperes.
- **Milliamps** (mA) — Current in milliamperes.
- **Apparent Power** (VA) — Apparent power in volt-amperes.
- **BTU/hr** (BTU/hr) — Heat equivalent in BTU per hour.

## Details

The relationship between watts, amps, and volts follows Ohm's law and the power equation. For DC circuits and purely resistive AC loads (power factor = 1), the formula is simply Amps = Watts / Volts. For AC circuits with inductive or capacitive loads, the power factor must be included.

Key formulas

- Amps (DC) = Watts ÷ Volts

- Amps (AC single-phase) = Watts ÷ (Volts × Power Factor)

- Apparent Power (VA) = Watts ÷ Power Factor

- BTU/hr = Watts × 3.41214

Common Electrical Reference

Device
Watts
Voltage
PF
Amps

LED Bulb
10
120 V
1.0
0.083

Microwave
1,000
120 V
0.95
8.77

Hair Dryer
1,500
120 V
1.0
12.5

Window AC
1,200
120 V
0.85
11.76

Electric Oven
2,400
240 V
1.0
10.0

EV Charger (L2)
7,200
240 V
1.0
30.0

The power factor describes how efficiently an AC circuit uses power. Purely resistive loads (heaters, incandescent bulbs) have a PF of 1.0. Motors, compressors, and fluorescent lighting typically have PFs of 0.8-0.95, meaning they draw more current than the wattage alone would suggest.

## Frequently Asked Questions

**Q: How do I convert watts to amps?**

A: For DC or resistive AC loads, divide watts by volts: Amps = Watts ÷ Volts. For AC loads with a power factor less than 1, divide by both: Amps = Watts ÷ (Volts × Power Factor). For example, 100W at 120V = 0.833 amps.

**Q: What is power factor?**

A: Power factor is the ratio of real power (watts) to apparent power (volt-amps) in an AC circuit. It ranges from 0 to 1. A power factor of 1 means all power is used productively. Motors and other inductive loads have power factors below 1, meaning they draw more current than a purely resistive load of the same wattage.

**Q: How many watts is a 15-amp circuit?**

A: A 15-amp circuit at 120V can handle up to 1,800 watts (15 × 120). However, the NEC recommends loading circuits to no more than 80% of capacity for continuous loads, which means 1,440 watts on a 15-amp circuit.

**Q: Why convert watts to BTU/hr?**

A: BTU/hr measures heat output, which is important for HVAC sizing and cooling calculations. Every watt of electrical power ultimately becomes heat. 1 watt equals 3.412 BTU/hr, so a 1,000W device produces about 3,412 BTU/hr of heat.

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Source: https://vastcalc.com/calculators/conversion/watts-to-amps
Category: Conversion
Last updated: 2026-04-21