What is the formula for resistors in series?

Resistances in series simply add — Rt = R1 + R2 + ... + Rn. The total is always larger than any single resistor.

How is series different from parallel?

In series the resistances add directly, increasing the total. In parallel the reciprocals add, so the total is smaller than the smallest resistor.

Why is series resistance larger than each resistor?

Because the current must pass through every resistor in turn, each one adds its own opposition to the path. The combined resistance is therefore the sum and always exceeds the largest single value.

How does adding a resistor in series affect current?

It reduces the current. By Ohm's law, current equals voltage divided by total resistance, so increasing the total resistance with another series resistor lowers the current for a fixed voltage.

Can I mix resistors of different values?

Yes. Series resistance does not require matched values — enter any mix of resistances and the tool sums them all.

Series Resistance Calculator

Q: Is anything uploaded?

No — every calculation runs locally in your browser, with no network requests.

Series resistance calculator

When resistors are wired in series — end to end in a single line — the same current flows through each one, so their resistances add up. This calculator totals any number of resistor values for you. It is for electronics hobbyists, students and engineers working out an equivalent resistance.

How it works

The total (equivalent) series resistance is simply the sum of the individual values:

R_t = R₁ + R₂ + … + R_n

Enter your values in ohms, separated by commas or spaces. The result is always larger than the biggest single resistor, because every resistor adds to the path.

This is the opposite of a parallel connection, where the reciprocals add and the total is smaller than the smallest resistor.

Example

Three resistors of 100 Ω, 220 Ω and 470 Ω in series:

R_t = 100 + 220 + 470 = 790 Ω

Resistors (Ω)	Series total (Ω)
100, 220, 470	790
1000, 1000	2000
330, 220	550

Every calculation runs locally in your browser, with no network requests.