Series Resistor Calculator

Calculate total resistance for resistors connected in series. Add as many resistors as you need — the circuit is illustrated automatically.

Up to 8 resistors.

Total resistance
30 Ω
Rtot = R1 + R2
Number of resistors
2
Highest single value
20 Ω

How to use the calculator

  1. Enter your resistors in ohms, one per row.
  2. Add more resistors with "+ Add resistor" — the circuit diagram updates automatically with one zigzag per resistor.
  3. The calculator shows the total resistance and how many resistors are in use.

How a series connection is calculated

With a series connection, the resistors sit one after another along the same current path. Current has to flow through every single resistor, so total resistance is simply the sum of all the resistors:

Rtot = R1 + R2 + R3 + … + Rn

The more resistors you connect in series, the higher the total resistance becomes — and total resistance is always higher than the highest single resistor in the combination.

Note: The order of the resistors in a series connection doesn't affect total resistance — only the sum matters. This is different from a parallel connection, see the parallel resistor calculator.

Frequently asked questions

Why is total resistance higher with a series connection?

With a series connection, current has to flow through every resistor one after another along the same path, so each resistor adds its own share of resistance. Total resistance is therefore always the sum of all the individual resistors.

How many resistors can I add?

The calculator supports up to 8 resistors in series. The principle is the same no matter how many: you simply add all the resistance values together.

What are series connections used for in practice?

Series connections are often used to divide a voltage or limit the current in a circuit, for example in simple LED circuits, or to build a specific resistance value by combining several standard values.