What is the formula for resistors in series?

For resistors in series, the total resistance R_total = R1 + R2 + R3 + ... + Rn. Each resistor value is simply added together.

Why does resistance increase in series?

In a series circuit, current must flow through every resistor one after another. Each resistor adds opposition to current flow, so the total opposition (resistance) grows with every resistor added.

Is there a limit to how many resistors I can add?

This calculator supports up to 10 resistors. In real circuits there is no theoretical limit, though practical constraints like power dissipation and physical space apply.

Can I mix ohms, kilohms, and megaohms?

Yes. Each resistor has its own unit selector. The calculator converts all values to ohms before summing, then displays the result in the most convenient unit.

How is this different from parallel resistance?

Series resistance is a simple sum. Parallel resistance uses the reciprocal formula: 1/R_total = 1/R1 + 1/R2 + ... The result for parallel combinations is always less than the smallest individual resistor.

Resistance Series Calculator

Name: Resistance Series Calculator
Availability: InStock
Author: Nham Vu

Add up to 10 resistors and instantly calculate their total series resistance with unit conversion.

Resistors in Series

Total Series Resistance

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Enter resistors to calculate

Series Resistance Formula

R_total = R₁ + R₂ + ... + R_n

Each resistor adds directly to the total. The more resistors in series, the higher the combined resistance.

Summary

Add up to 10 resistors and instantly calculate their total series resistance with unit conversion.

How it works

Enter the value of the first resistor and select its unit (Ohms, Kilohms, or Megaohms).
Click "Add Resistor" to insert additional resistors as needed (up to 10).
All values are converted to ohms internally and summed.
The total resistance is displayed in the most readable unit automatically.
Remove any resistor by clicking the delete button next to it.
Click "Reset" to start over with a fresh set of inputs.

Use cases

Calculate the combined resistance of a resistor ladder network.
Verify series resistor values when designing current-limiting circuits.
Sum resistor tolerances to estimate worst-case total resistance.
Quickly convert mixed ohm/kilohm/megaohm resistor values into a single total.
Educational use: verify textbook series-resistance problems.
Prototype LED current-limiting resistor chains.
Plan pull-up or pull-down resistor dividers for microcontroller inputs.
Calculate bias resistor chains for transistor base networks.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu