Series and Parallel Resistor Calculator

Use this calculator to find the total resistance of resistors connected in series or in parallel.

Resistors in series add up. In parallel, the total is always lower than the smallest resistor:

R_{ser i es} = R_{1} + R_{2} + R_{3} + \dots \frac{1}{R _{p a r a l l e l}} = \frac{1}{R _{1}} + \frac{1}{R _{2}} + \frac{1}{R _{3}} + \dots

Choose series or parallel, and fill in your resistor values. Click “Add resistor” for more than three:

SeriesParallel

Resistor 1

Resistor 2

Resistor 3

Total resistance: -
Resistors: -

Handy to Know

Two equal resistors in parallel give you half the value. Two 1 kΩ resistors in parallel make 500 Ω, and two in series make 2 kΩ. So if you don’t have the exact resistor you need, you can often make it from two others.

Want to learn more? Read about series and parallel circuits, or find a resistor’s value with the resistor color code calculator.