Resistance Combiner
Resistors
Choose the connection, then add or remove values.
Total resistance
How to use this calculator
Combine any number of resistors. In series the resistances simply add: R = R1 + R2 + … + Rn. In parallel the reciprocals add: 1/R = 1/R1 + 1/R2 + … + 1/Rn. Toggle between the two modes, add or remove rows with a value and unit (Ω, kΩ, MΩ), and the total updates in real time. The series total is always at least the largest resistor; the parallel total is always smaller than the smallest.
What it means in a real circuit
Real circuits rarely have a single part with the exact value you need, so combining resistors is a daily skill: a series pair to set a current limit or a precise divider ratio, a parallel pair to get a lower value or a higher power rating, or a series-parallel network to hit a target impedance. Knowing the two combining rules by heart lets you verify a board, substitute parts, or design a value from the resistors you actually have in the bin.