Parallel Resistor Calculator

Parallel resistor calculator is a useful tool to solve two or more than two resistors in parallel. It is used to calculate equivalent resistance of the parallel resistor.

What are Parallel Resistors

There are three basic configurations in which we can arrange the electrical components.

  1. Series configuration
  2. Parallel Configuration
  3. Series-Parallel Configuration

In series, configuration components are simply joined as one next to the other. A parallel configuration, on the other hand, is complex to understand. One can simply understand the parallel configuration by the following definition.

Two or more components are in parallel if the one end of all components are connected together to a common node, and the tails are connected together to the other common node, and there is no other connection in between them.

The figure below displays three resistors R1, R2, and R3.


The upper terminal of all resistors shares the red node on the top. Whereas the lower terminal of resistors shares the orange node. Since this condition satisfies the condition of parallel resistors, our circuit is a parallel circuit.

Parallel Resistor Formula | How to solve Parallel Resistors

The general formula for solving parallel resistors is:


Where n is the number of resistors and Req is overall resistance which appears across the red and orange node.

In the previous case of three parallel resistors, we can apply the formula:

formula-to-solve-three-parallel-resistors (1)

Let’s consider the case of two parallel resistors.


Let’s solve some numerical example problems to better learn it.

Example # 1: Two parallel resistors of 5 Ω and 20 Ω connect in parallel. Find the equivalent resistance.


1 / Req= [1/R1] + [1/R2]

1 / Req= [1/5 Ω] + [1/20 Ω]

1 / Req= [0.2] + [0.05]

1 / Req= 0.25 Ω

Req= 4 Ω

Example # 2: Two parallel resistors of 12 Ω each are joined in the parallel configuration. Find the overall equivalent resistance of circuit.

Solution: DIY Req= 6 Ω

Electrical Calculators © 2018