Engineering & Science
Ohm's Law Calculator
Choose the value to solve for, then enter two known electrical values to calculate voltage, current, resistance, or power.
Inputs
Results
Useful next checks
- Check the inputs before relying on the result.
- Try a second scenario to compare outcomes.
- Read the guide below for context.
# Ohm's Law Calculator
Use this Ohm's law calculator to solve for voltage, current, resistance, or power from two compatible electrical values.
What this calculator does
Choose the value you want to calculate, then enter known values for voltage, current, resistance, or power. The calculator selects a compatible formula and returns the target value with units.
How it works
The core formulas are `V = I x R` and `P = V x I`. Equivalent forms include `I = V / R`, `R = V / I`, `P = I^2 x R`, and `V = square root(P x R)`.
Example calculation
If current is 2 A and resistance is 6 ohms, voltage is `2 x 6 = 12 V`. If voltage is 12 V and current is 2 A, power is `12 x 2 = 24 W`.
How to use the result
Use the result as a formula check for simple DC-style calculations. Confirm ratings, tolerances, and safety requirements before building or modifying real circuits.
Assumptions and limitations
This calculator assumes ideal values and does not model AC phase angle, temperature effects, component tolerance, wiring losses, inrush current, or safety limits.
FAQs
Which two values do I need?
Any two compatible known values can work. For example, voltage plus current can calculate power or resistance.
Does it handle AC circuits?
Only as a simple arithmetic reference. AC circuit design may need impedance, power factor, and RMS values.
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Frequently asked questions
Which formulas are used?
The calculator uses V = I x R and P = V x I, plus equivalent rearrangements.
Do I need to clear the value I am solving for?
No. The selected target is ignored and recalculated from the other fields.