---
title: "How Many Watts Per Amp?"
canonical: "https://ampstowatt.com/how-many-watts-per-amp/"
author: ""
published: "2026-09-05T09:09:50+00:00"
modified: "2026-09-05T09:09:50+00:00"
language: "en-US"
site: "Ampstowatt"
description: "One amp equals 12W at 12V, 120W at 120V, and 240W at 240V. The answer depends on voltage. See the complete formula, full table, and real examples."
attribution: "Ampstowatt (https://ampstowatt.com/)"
---

# How Many Watts Per Amp?

One ampere equals a different number of watts depending on the circuit voltage. At 12 volts, 1 amp = 12 watts. At 120 volts, 1 amp = 120 watts. At 240 volts, 1 amp = 240 watts. The formula is: Watts = Amps × Volts.

 

To calculate for any specific voltage, use the [Amps to Watts Calculator](/).

 

## Watts Per Amp at Common Voltages

 

| Circuit Voltage | Watts per 1 Amp | Common Use |
| --- | --- | --- |
| 5 V | 5 W | USB charging |
| 9 V | 9 W | Small DC devices |
| 12 V | 12 W | Automotive, RV, solar |
| 24 V | 24 W | LED drivers, some DC systems |
| 48 V | 48 W | Telecom, solar battery |
| 120 V | 120 W | US household outlets |
| 208 V | 208 W | Commercial 3-phase (Y) |
| 220 V | 220 W | International appliances |
| 230 V | 230 W | UK, EU mains |
| 240 V | 240 W | US split-phase, AU/NZ |
| 277 V | 277 W | Commercial lighting |
| 480 V | 480 W | Industrial 3-phase |

 

## The Formula: Why Watts Depend on Voltage

 

Watts per amp isn’t a fixed number — it scales directly with voltage because of Watt’s Law: P = I × V.

 

### Why Isn’t There a Fixed “Watts Per Amp” Answer?

 

Unlike a fixed conversion (like 1 mile = 1.609 km), watts per amp requires voltage as an input. Without voltage, the conversion is incomplete.

 

### DC vs AC Watts Per Amp

 

For DC circuits, watts per amp = voltage (simple multiplication, no power factor).

 

For AC circuits with inductive loads, real watts per amp = voltage × [power factor](/power-factor/).

 

Example: On a 120V AC circuit with a motor at PF 0.85: Watts per amp = 120 × 0.85 = **102 real watts per amp** (not 120W).

 

## Frequently Asked Questions

 

### How many watts is 1 amp?

 

1 amp equals 120 watts at 120 volts, or 240 watts at 240 volts. In a 12V DC system, 1 amp equals 12 watts.

 

### Is there a fixed number of watts per amp?

 

No, watts per amp is not fixed. It changes depending on the voltage of the circuit.

 

### What is 1 amp at 120 volts?

 

1 amp at 120 volts is exactly 120 watts for a resistive load.

 

### How does power factor change watts per amp?

 

In AC circuits with inductive loads, you must multiply the apparent power (V × A) by the power factor (PF) to get real watts per amp. This means the real watts will be lower than the apparent watts if the PF is less than 1.0.

      Hub  

## Apply This Knowledge

     **Start with the main conversion tool** 

Use these calculator pages to apply the concept to real current, voltage, watts, and power-factor problems.[Amps to Watts Calculator](/)

  [W**Amps to Watts Calculator**Main calculator hub and formula reference](/)[AC**AC Amps to Watts Calculator**Apply power factor to AC current](/ac-amps-to-watts-calculator/)[DC**DC Amps to Watts Calculator**Use the direct DC watts formula](/dc-amps-to-watts-calculator/)[A**Watts to Amps Calculator**Find current from known watts and volts](/watts-to-amps-calculator/)[FX**Amps to Watts Formula**Review the formulas behind the tools](/amps-to-watts-formula/)[TAB**Conversion Charts**Compare common amp, volt, and watt values](/conversion-charts/)[PF**Power Factor**Understand real power in AC circuits](/power-factor/)     Advertisement