Series & Parallel Resistor Calculator

Series & Parallel Resistor Calculator

Quickly determine the equivalent resistance of varying circuit topologies with our Series & Parallel Resistor Calculator. Whether your resistors are wired in series or parallel, enter up to 10 resistor values to instantly compute the total equivalent resistance. By providing an optional Total Voltage, you can also uncover the voltage drop across each resistor and the precise current flowing through them using voltage divider and current divider rules.

2 / 10 limit
Provide total voltage to calculate current & voltage drop across each resistor.
Please enter valid resistance values.
Equivalent Resistance (RTotal)
0 Ω

The Differences Between Series & Parallel Circuits

Resistors can be connected in complex networks, but these networks are typically broken down into two essential orientations: Series and Parallel.

  • Series Configuration: Resistors are placed end-to-end. There is only one path for the current to flow, meaning the current through each resistor is exactly the same, but the voltage drops across them. The equivalent resistance is the simple sum of all resistors: R_total = R₁ + R₂ + ... + Rₙ. Adding more resistors in series increases the total resistance.
  • Parallel Configuration: Resistors are placed side-by-side, sharing the same two nodes. This means the voltage across each resistor is identical, but the current splits among the parallel branches based on their resistance (current takes the path of least resistance). The equivalent resistance is found using the inverse sum: 1/R_total = 1/R₁ + 1/R₂ + ... + 1/Rₙ. Adding more resistors in parallel decreases the total resistance completely.