Series and Parallel Resistance Calculator
Resistors in Series
Rtotal = R1 + R2 + R3 + ...
Resistors in Parallel
1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ...
Resistance Formulas
Series Resistance
Rtotal = R1 + R2 + R3 + ...
In series, resistances add up. Total resistance is always greater than any individual resistor.
Parallel Resistance
1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ...
In parallel, total resistance is always less than the smallest resistor.
Two Resistors in Parallel
Rtotal = (R1 × R2) / (R1 + R2)
This simplified formula works for exactly two resistors.