# Series Resistor Calculator

Our series resistor calculator is the perfect tool to **find the equivalent resistance of a circuit consisting of up to ten resistors connected in series.**

This calculator can also be called *equivalent resistance calculator for resistors in series* or *circuit resistance calculator*.

Keep reading while we show you the series resistance formula and how to calculate resistance in a series circuit. Let's begin!

## What is a resistor?

A resistor is an electrical component that *resists* the current flow within a circuit.

Ohm's law indicates how much a resistor impedes this flow of current:

where:

- $V$ is the voltage difference across the resistor, in volts;
- $R$ is the resistor's resistance in ohms (the series resistor calculator has a built-in unit switcher, allowing you to input resistance in other units); and
- $I$ is the resulting current, in amperes.

💡 As current flows through a resistor, the resistor gets heated. Read more about this in the power dissipation calculator!

## How to calculate resistance in a series circuit — resistors in series formula

When we connect resistors in series, **the current is the same through each of them**. Because of that, we can find the total voltage drop across the resistors by adding the individual voltages across each resistor:

where:

- $V$ is the total voltage difference across all the resistors.
- $V_{i}$ are the individual voltage differences.
- $I$ is the current flowing through the resistors.
- $R_{i}$ are the individual resistances. You can input up to ten resistors in our series resistor calculator.

🔎 Look at our parallel resistor calculator and see how it differs from this tool!

Notice that here the current is a common $I$ factor in every term, and if we factor out this current, we're left with:

This expression looks a lot like Ohm's law, and if we group all these resistances in a single term, the similarity becomes more evident:

$R_{eq}$ is what we call the **equivalent resistance** of the circuit.

When we connect the resistors *in series*, the equivalent resistance acts as a single resistance equal to the **sum of all the individual resistances** as seen in the resistors in series formula:

🙋 Use our series resistor calculator to find the equivalent resistance easily! Simply input the resistance of each resistor, and our equivalent resistance calculator will do the rest.

## Other features of our series resistor calculator

This calculator already has the **series resistance formula** within it, and it's smart enough to find the **missing resistance** given the equivalent resistance and all other resistance values.

Select the **calculate missing resistor** mode and experiment with it!

*Input at least one resistor to obtain a result*.