100 Watts to Amps
100 W is 0.4348 A at 230 V and 0.8333 A at 120 V (single-phase, power factor 1). Table for DC and three-phase, power factor 0.8, and the formula.
Formula
Worked example
- I = 100 / (230 × 1) = 0.4348 A
- With a power factor of 0.9: I = 100 / (230 × 0.9) = 0.4831 A
On other supplies
| Supply | Voltage | Current at pf 1 | Current at pf 0.8 |
|---|---|---|---|
| DC | 12 V | 8.333 A | not used |
| DC | 24 V | 4.167 A | not used |
| DC | 48 V | 2.083 A | not used |
| Single-phase | 120 V | 0.8333 A | 1.042 A |
| Single-phase | 230 V | 0.4348 A | 0.5435 A |
| Single-phase | 240 V | 0.4167 A | 0.5208 A |
| Three-phase | 208 V | 0.2776 A | 0.347 A |
| Three-phase | 400 V | 0.1443 A | 0.1804 A |
| Three-phase | 415 V | 0.1391 A | 0.1739 A |
| Three-phase | 480 V | 0.1203 A | 0.1504 A |
Three-phase rows use the line-to-line voltage. DC ignores the power factor.
What 100 W looks like
100 W is about the load of a bright incandescent lamp, a ceiling fan or a laptop working hard.
This is an estimate of the load current only. Choosing a cable or a breaker also needs the installation method, the ambient temperature, the voltage drop and the rules you work to.
Frequently asked questions
How many amps is 100 watts?
100 W is 0.4348 A on a 230 V single-phase supply and 0.8333 A on 120 V, both with a power factor of 1. The current depends on the voltage, so it is a different answer on every supply.
What if the power factor is not 1?
The current rises. At 230 V and a power factor of 0.9, 100 W draws 0.4831 A. Heaters and filament lamps are close to 1, while motors and many power supplies are lower.
What about a three-phase supply?
100 W on 400 V three-phase at a power factor of 0.8 is 0.1804 A. The line voltage is used with the factor √3 (about 1.732).
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