Series Resistance Calculator

R_total = R₁ + R₂ + R₃ + … — find equivalent resistance of resistors in series.

Inputs

Result

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General calculation reads

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How to use this calculator

  • Enter values separated by commas.
  • Read the total.

About this calculator

Resistors in series simply add: R_total = R₁ + R₂ + R₃ + … Current is the same through every series element; voltage divides in proportion to resistance. The opposite combinatorics from parallel — series adds, parallel uses reciprocals.

Frequently asked

Why does series resistance just add?+
Because the same current flows through every series element, and the voltage drops add up to the source voltage. V = IR shows that R must add too.
How do voltages divide in series?+
In proportion to each resistance. V_n = V_total × R_n / R_total. This is the voltage divider formula.
What's the same across series resistors?+
Current. All series elements see identical current.
When is series useful?+
Voltage dividers, current limiters (e.g. in series with an LED), pull-up/pull-down resistors.
Combining series and parallel?+
Reduce groups step-by-step. First simplify any pure series or pure parallel sub-blocks, then combine the simplified groups.

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