How parallel resistance works
When resistors are connected in parallel, the total (equivalent) resistance is always less than the smallest individual resistor. It’s found using the reciprocal formula: 1/Rtotal = 1/R1 + 1/R2 + 1/R3 + 1/R4 (add a term for each resistor in the circuit).
How this calculator works
Enter the resistance values for up to four resistors wired in parallel. Leave any unused resistor slots set to 0. The calculator adds up the reciprocals of each active resistor’s value, then takes the reciprocal of that sum to give the total equivalent resistance of the parallel combination.
Adding more resistors in parallel always lowers the total resistance and increases the total current the combination can draw for a given voltage. This calculator is for general electronics education and planning purposes.