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Ohm Law and Electrical Power Calculator
An Ohm law calculator for finding voltage, current, resistance, and electrical power from any two values you know.
Choose the two values you know, then enter them. The circuit derives the remaining pair in SI units.
Enter two positive values to begin.Choose two known values
Two known terminals create the missing pair.
Start from a real load
Complete the circuit
Choose two terminals to complete the circuit.
V I R PChoose two terminals to complete the circuit.
Lit terminals are known. Copper traces show the equations.
Circuit readout
Two known terminals create the missing pair.
CurrentA
— Two known terminals create the missing pair. ResistanceΩ
— Two known terminals create the missing pair. PowerW
— Two known terminals create the missing pair. Zoom 100%
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Frequently Asked Questions
I know voltage and current. What do I get?
You get resistance and power. For example, 12 V and 2 A produce 6 Ω and 24 W.
Can this calculate the wattage for a resistor?
Yes. Enter the voltage and resistance, or the current and resistance, to calculate the power the resistor dissipates.
Can I use power and voltage as my inputs?
Yes. Enter both values and the calculator derives current with I = P / V and resistance with R = V² / P.
Does Ohm law apply to every electronic component?
No. This calculator models a simple ohmic component. Devices such as diodes have a nonlinear relationship between voltage and current.
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