# How to Calculate Resistors in Series and Parallel

## Resistors in Series

When resistors are connected one after each other this is called connecting in series. This is shown below.

To calculate the total overall resistance of a number of resistors connected in this way you add up the individual resistances. This is done using the following formula:

Rtotal = R1 + R2 +R3 and so on.

Example: To calculate the total resistance for these three resistors in series.

Calculate the total resistance of the following resistor in series.

### Resistors in Parallel

When resistors are connected across each other (side by side) this is called connecting in parallel. This is shown below.

### Two Resistors in Parallel

Example: To calculate the total resistance for these two resistors in parallel.

Calculate the total resistance of the following resistor in parallel.

### Three or more resistors in parallel

To calculate the total overall resistance of a number of three or more resistors connected in this way you can use the following formula:

Example: To calculate the total resistance for these three resistors in parallel

Calculate the total resistance of the following resistor in parallel.

1 = 1492 Ohms

2 = 2242 Ohms

3 = 4847 Ohms

1 = 5 Ohms

2 = 9.57 Ohms

3 = 248.12 Ohms