Parallel resistors calculator

by Gabriel Rapetti and Inventable.eu

Enter the value of the resistor you want to obtain, select the multiplier (right next to the value) and press the "CALC" button. The calculator will display the pair of resistors whose parallel will be the closest value to the value you enter. At the same time, it will display the resulting equivalent value and a picture of the resistors to be used.

Resistance value
ΩKΩMΩ

Resistor 1

Resistor 2

Calculated value

always use two resistors

Description

This program allows us to obtain the closest equivalent resistance to the desired value using only two E12 series resistors connected in parallel. We have chosen the E12 series because it is by far the most widely used in electronics.
The values belonging to this series are: 10, 12, 15, 18, 22, 27, 33,  39, 47, 56, 68 and 82. Each of these values (1st and 2nd digit or color band) multiplied by the 3rd digit or color band (the multiplier) results in the full range of values available in this series.

The option "always use two resistors" forces the calculator to always use two resistors, even if the result can be obtained with only one. This option is very useful if you need a standard value, but do not have it available.
The equivalent value of two resistors connected in parallel can be calculated using one of the following formulas:

The formula on the left is generic and can be extended to any number of resistors. The other is its simplification for two resistors only.

This work is original and is licensed under a Creative Commons BY-NC-ND license. Creative Commons BY-NC-ND