This parallel resistance calculator finds the equivalent resistance of two or more resistors wired in parallel. Enter your resistor values above to get the total resistance in ohms.
Formula
1 ÷ Rtotal = 1/R₁ + 1/R₂ + 1/R₃ + ...
The equivalent parallel resistance is always smaller than the smallest resistor in the group.
Example
10, 20, and 30 Ω in parallel: 1/R = 0.1 + 0.05 + 0.0333 → R = 5.45 Ω.
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Frequently Asked Questions
How do I calculate parallel resistance?
Add the reciprocals of each resistor, then take the reciprocal of the sum. Two 10-ohm resistors give 5 ohms.
Is parallel resistance smaller than each resistor?
Yes, always. The combined value is lower than the smallest resistor in the parallel group.
What about two equal resistors in parallel?
The result is exactly half of one resistor’s value.