Ohm's Law Calculator
Solve for voltage, current, or resistance — leave one field blank and the Ohm's Law calculator will find the missing value from the other two.
Leave exactly one field blank to calculate that value.
Result
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How to Use This Calculator
Fill in any two of the three fields and leave the third blank. The calculator will automatically solve for the missing quantity using Ohm's Law. All three modes (find V, find I, find R) are supported.
Formula
Ohm's Law defines the relationship between voltage, current, and resistance in a linear circuit:
V = I × R
I = V / R
R = V / I
Example
Find current: 9V battery, 470 Ω resistor
I = V / R = 9 / 470
I ≈ 0.01915 A (19.15 mA)
Find resistance: 5V source, 100 mA load
R = V / I = 5 / 0.1
R = 50 Ω
I = V / R = 9 / 470
I ≈ 0.01915 A (19.15 mA)
Find resistance: 5V source, 100 mA load
R = V / I = 5 / 0.1
R = 50 Ω