Watt And Ampere Calculator
Calculate electrical power (watts), current (amperes), voltage (volts), or resistance (ohms) using Watt's law and Ohm's law. Enter any two values to compute the others.
Published by:
isCalculator Editorial Team
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How to use this tool?
This calculator uses Ohm’s Law and the power formula to compute the two missing electrical values when you provide any two known values.
- Enter exactly two values into the fields: Voltage (V), Current (A), Power (W), or Resistance (Ω). Leave the other two fields empty.
- Click “Calculate” (or press Enter). The calculator will compute the remaining two values.
- Read the results displayed in green. Each result shows up to 4 decimal places.
- Check the formula shown below the results to see which equations were used.
Important: Use consistent units (e.g., volts, amperes, watts, ohms). All values must be positive numbers. If you see an error, ensure you entered exactly two non-empty fields.
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Frequently Asked Questions
Watts measure electrical power (rate of energy transfer), while amperes measure electrical current (flow of electric charge). They are related by voltage: Power (W) = Voltage (V) × Current (A).
Yes, if you enter voltage and current, the calculator will compute resistance using Ohm's law: R = V / I. Similarly, other combinations can yield resistance.
Ensure you enter exactly two numeric values and leave the other two fields empty. Check that values are positive and non-zero where applicable (e.g., voltage or current cannot be zero for some calculations).