# Series Resistance Calculator

> Calculate series resistance step by step: R_total = R1 + R2 + … + Rn.

Page: https://freecalculator.tech/tools/series-resistance-calculator
Last reviewed: 2026-11-03

## Formula

R_total = R1 + R2 + … + Rn.

- The same current flows through every resistor in series.
- Blank optional boxes are skipped; negative values are rejected.
- With a supply voltage, current = V ÷ R_total.
- R_total = R1 + R2 + … + Rn.
- Inputs used: R1, R2, R3 (optional), R4 (optional), R5 (optional), Supply voltage (optional).

## Inputs

- R1
- R2
- R3 (optional)
- R4 (optional)
- R5 (optional)
- Supply voltage (optional)

## Worked example: 100 Ω + 220 Ω + 330 Ω

Three resistors in a chain.
1. 100 + 220 + 330 = 650 Ω.

## Common questions

### Why is the total always larger than any single resistor?

Current has to pass through every resistor in turn, so each one adds opposition.

### How is voltage shared?

Each resistor drops V × (its R ÷ total R). That is the principle behind the voltage divider calculator.

### What if one resistor fails open?

The whole series chain stops conducting, because there is only one path for current.

### How do I use the Series Resistance Calculator?

Enter the required values for R1, R2, R3 (optional), R4 (optional), R5 (optional), and the other fields shown. The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.

### What formula does the Series Resistance Calculator use?

R_total = R1 + R2 + … + Rn. The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone.

### Can the Series Resistance Calculator be used for exact decisions?

Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.

## Limitations and assumptions

- Up to five resistors.
- Ignores tolerance and temperature drift.
- Ideal wires with zero resistance assumed.
- Results are estimates for planning and learning. Real designs, installations and bids must be checked by a qualified, licensed professional against the codes that apply where you work.
- The result depends on the values you enter for this series resistance calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.

## Sources

- OpenStax (Rice University) — https://openstax.org/details/books/university-physics-volume-2

## Cite this page

- APA: Free Calculator. (2026, November 3). Series Resistance Calculator. https://freecalculator.tech/tools/series-resistance-calculator
- MLA: "Series Resistance Calculator." Free Calculator, 3 Nov. 2026, https://freecalculator.tech/tools/series-resistance-calculator.
- Link: Series Resistance Calculator — Free Calculator, https://freecalculator.tech/tools/series-resistance-calculator