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Solve voltage, current, resistance, and power from any two knowns (V=IR, P=VI).
Ohm's Law Calculator is loading — interactive editor will appear here. Use examples below to try instantly once loaded.
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Solves Ohm's Law: enter any two of voltage, current, resistance, or power, and the calculator computes the other two.
Ohm's law (V = I×R) plus the power identity (P = V×I) reappears in electronics, automotive, and home-wiring work. Solving it by hand for every pair (V/P? I/R?) means remembering six algebraic rearrangements; this tool does it for you.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
Electronics hobbyists, automotive electricians, EE students, and anyone sizing circuits, fuses, or wiring.
Enter any two of V (volts), I (amps), R (ohms), P (watts)
Leave the other two fields blank
Read all four values in the results panel
Negative or non-physical inputs produce an error rather than nonsense
V = 12, R = 6 Ω → I = 2 A, P = 24 WP = 100 W, R = 50 Ω → V ≈ 70.7 V, I ≈ 1.41 AV = 120 V, I = 2 A → R = 60 Ω, P = 240 WP = 1500 W, V = 120 V → I = 12.5 A, R = 9.6 ΩQ: What if I know only one value? A: Ohm's law needs two
you can only solve a single unknown from the pair.
Q: Does it handle series and parallel? A: Not here
use the Resistor Calculator for networks, then feed the equivalent resistance into Ohm's law.
Q: Can I use this for AC? A: For purely resistive AC loads, yes, using RMS values. Motors and ballasts need power factor
this tool is DC/pure-resistive only.
Q: How are negative values handled? A: They're rejected
power, resistance, and magnitude of V/I are non-negative in this model.
Authoritative specifications, standards, and in-depth reading for Ohm's Law Calculator.
Fill any two fields; the other two are solved. Leave extra fields blank.
Voltage
12 V
Current
2 A
Resistance
6 Ω
Power
24 W
Ohm’s law: V = I × R. Power: P = V × I = I²R = V²/R. Runs locally.
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