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Science & Engineering Calculator
Ohm’s Law Power Calculator
Calculate voltage, current, resistance and power from any two known electrical values using Ohm’s law and power formulas.
Voltage, current, resistance and power
Enter any two known positive values. The calculator chooses the first complete pair in this order: V+A, V+R, V+W, A+R, A+W, R+W.
Voltage–
Current–
Resistance–
Power–
Enter any two values to calculate the remaining electrical values.
Ohm’s law and power formulas
V = I x R
P = V x I
P = I^2 x R and P = V^2 / R
These formulas connect voltage, current, resistance and power in simple DC and resistive circuit calculations.
When to use this calculator
- Estimate wattage when you know voltage and current.
- Find resistor value when you know voltage and desired current.
- Check current draw from power and voltage.
- Use proper electrical safety rules and rated components for real circuits.
Ohm’s Law Power Calculator FAQ
What values do I need?
Enter any two positive values among voltage, current, resistance and power.
What is the power formula?
Electrical power is P = V x I, where P is watts, V is volts and I is amps.
What is Ohm’s law?
Ohm’s law is V = I x R, connecting voltage, current and resistance.
Can I use this for AC circuits?
It is best for DC or simple resistive AC loads. AC circuits with power factor or reactance need additional calculations.
Why are my extra input values ignored?
If more than two values are entered, the calculator uses the first complete pair in the displayed priority order.
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