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Ohm's Law Calculator (Voltage · Current · Resistance · Power)

Feed any two of voltage, current, resistance, or power and the remaining quantities snap into place.

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Solve any two-to-four relationship instantly

Feed any two of voltage, current, resistance, or power and the remaining quantities snap into place. Unit switching, sharable URLs, and a local favourites toggle keep everyday circuit checks fast.

Inputs

Use mV for sensor rails and kV for high-voltage systems.

Instrumentation loops often run in µA or mA, power stages in amps.

Select milliohms for shunts, kiloohms or megaohms for bias networks.

Portable gear typically uses mW, motors and heaters use watts or kW.

Equations & usage notes

The calculator picks the appropriate formula set for the pair you provide and verifies consistency against Ohm's law.

V = I × R
P = V × I
I = P ÷ V
R = V ÷ I
I = √(P ÷ R)

This tool is for rapid estimation and learning. Always validate designs with lab measurements and relevant safety standards.

FAQ

Which unit should I pick?

Pick mA or µA for tiny currents and kΩ or MΩ for large resistances. Results always follow the units you choose.

What if the numbers disagree with the result?

If any inputs contradict Ohm's law the calculator flags an error. Double-check the values when the mismatch is larger than rounding tolerance.

Can I rely on this for safety sign-off?

This tool is for rapid estimation and education. It does not replace safety standards, hardware validation, or professional review.

How it's calculated

Cara pengiraan

  • Identiti asas: V = I·R dan P = V·I; dua nilai mencukupi untuk dapatkan dua lagi.
  • Ketakselarasan > ~0.5% akan diberi amaran untuk semakan nilai/unit.
  • Pengiraan dalam unit asas (V/A/Ω/W); awalan hanya mempengaruhi paparan.