Watts to Amps Calculator
Quick explanation
Use this calculator when you know power and voltage and need current. For the reverse direction, try amps to watts, or compare formula relationships in the Ohm's Law calculator. For the full formula walkthrough, see the how to convert watts to amps guide.
Estimated current: 15 A
How to convert watts to amps
To convert watts to amps, you need both power and voltage. Watts and amps do not represent the same quantity, so voltage is required to connect them.
Use these formulas as practical planning estimates. Real systems can vary with power factor, supply variation, and equipment behavior.
How to convert
Basic conversion formula
Current in amps equals power in watts divided by voltage in volts.
A = W / V
amps = watts / volts
Equivalent inverse formula
If you need the reverse conversion, compute watts from amps and volts.
W = A × V
Worked examples
Question: What is the current for 1800 W at 120 V?
Solution: A = 1800 / 120 = 15 A
Question: What is the current for 2400 W at 240 V?
Solution: A = 2400 / 240 = 10 A
Common mistakes and notes
- Do not divide by zero. Voltage must be greater than 0.
- For AC motors and mixed loads, real measured current may differ from nameplate estimates.
- Use this as a planning check, then verify with equipment documentation and code requirements.
Assumptions
- Uses simplified AC/DC planning math with nominal voltage.
- Does not account for power factor or startup surges.
- Use code-compliant methods for final sizing decisions.
Worked example
Example: 1800 W at 120 V = 15 A.
FAQ
How do you convert watts to amps?
Divide watts by volts: A = W / V.
How many amps is 1200 watts at 120 volts?
1200 W / 120 V = 10 A.
Why can measured amps differ from this result?
Real loads vary with power factor, voltage drift, and startup behavior.
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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.