Article
Amps to Watts at 120V and 240V: Practical Comparison
This page helps users translate current readings into power values under two common voltage contexts.
Why this query matters
Current readings are common during troubleshooting while labels and planning sheets usually use watts.
The same amps value maps to very different watts when voltage changes.
Common mistakes
Users often treat amps as universal power without carrying voltage assumptions.
Always compute watts with explicit voltage and keep assumptions in the output.
Practical workflow
Use reference values for quick checks and converter pages for uncommon current inputs.
Keep a separate row for each voltage context in your planning sheet.
Practical examples
- 10 A at 120V is 1200 W.
- 10 A at 240V is 2400 W.
- 15 A at 120V is 1800 W.
Amps-to-watts matrix
| Amps | 120V watts | 240V watts |
|---|---|---|
| 10 | 1200 | 2400 |
| 12 | 1440 | 2880 |
| 15 | 1800 | 3600 |
FAQ
Can I convert amps without voltage?
No. Voltage is required for meaningful conversion.
Is 15A at 120V equal to 1800W?
Yes under the baseline formula.
What if advanced electrical factors apply?
Use a full electrical model beyond this baseline conversion.
Editorial note
- These articles are written to explain why the conversion matters in real use, not only how the formula works.
- All linked calculators and fixed-answer pages use the same source formulas shown on the site.
- Last reviewed: March 26, 2026.