What units does this calculator use?

All results are displayed in engineering notation with SI prefixes: mV, A, kΩ, mW, etc. You can enter values with suffixes like 'k' (kilo), 'm' (milli), 'u' or 'µ' (micro), and 'n' (nano).

Can I calculate power from voltage and resistance?

Yes. While this calculator asks for two direct inputs per mode, the power is always shown alongside V, I, and R in the results panel. The formula P = V²/R is applied automatically when the relevant values are known.

Ohm's Law Calculator

Enter any two values — voltage (V), current (I), resistance (R), or power (P) — and instantly calculate the rest. Results are shown in engineering notation with auto-scaling units.

Voltage (V) Current (A) Resistance (Ω) Power (W)

Voltage (V)

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Current (A)

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Resistance (Ω)

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Power (W)

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Ohm's Law Triangle

V = I × R · I = V / R · R = V / I · P = V × I

All Formulas

Voltage (V)
V = I × R
V = P / I
V = √(P × R)
Current (A)
I = V / R
I = P / V
I = √(P / R)
Resistance (Ω)
R = V / I
R = V² / P
R = P / I²
Power (W)
P = V × I
P = V² / R
P = I² × R

What Is Ohm's Law?

Ohm's Law states that the current through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance: V = I × R. Named after Georg Simon Ohm, this fundamental relationship is the cornerstone of circuit analysis and applies to any resistive element from a simple resistor to complex loads.

Power in Circuits

Electrical power (P) measures the rate of energy transfer. It can be calculated from any two of V, I, and R: P = V × I, P = I²R, or P = V²/R. Understanding power is critical for selecting component ratings — exceeding a resistor's power rating will cause overheating and failure.

Ohm's Law Calculator

Ohm's Law Triangle

All Formulas

What Is Ohm's Law?

Power in Circuits

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