Volts to Watts Calculator
Quick explanation
Convert volts and amps into watts for quick equipment planning checks. You can also run the inverse flow with watts to amps and compare with amps to watts.
Estimated power: 1800 W
How to convert volts to watts
To estimate watts, multiply voltage by current. You need both values because volts alone cannot be converted directly into watts.
This tool is useful for quick appliance, circuit, or branch-load checks before deeper design work.
How to convert
Power formula
Power in watts equals voltage in volts multiplied by current in amps.
W = V × A
watts = volts × amps
Inverse relationship
If you already know watts and volts, you can find amps.
A = W / V
Worked examples
Question: How many watts is 120 V at 15 A?
Solution: W = 120 × 15 = 1800 W
Question: How many watts is 230 V at 8 A?
Solution: W = 230 × 8 = 1840 W
Common mistakes and notes
- Power factor is not included in this basic estimate.
- Use measured voltage when possible for better planning accuracy.
- Confirm final sizing with local code and equipment requirements.
Assumptions
- Uses nominal voltage and current values.
- Reactive loads and power factor effects are excluded.
- Treat output as planning guidance, not final design approval.
Worked example
Example: 240 V at 10 A = 2,400 W.
FAQ
How do you calculate watts from volts?
Multiply volts by amps: W = V x A.
What is 120 volts at 15 amps in watts?
120 x 15 = 1800 watts.
Can I use this for breaker sizing?
Use it for quick planning only and verify with code and equipment specs.
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⚠️ Sanity Check Only
This tool provides informational estimates only. It is not professional engineering advice. Electrical work is dangerous and governed by strict local codes.
Before you start:
- Verify these results with a licensed electrician.
- Cross-reference with the latest Electrical Code (NEC/CEC).
- Never work on live circuits.