Equivalent Resistance
0 Ω
0 Ω

A Parallel Resistor Calculator is a free online tool that helps you calculate the equivalent resistance of multiple resistors connected in parallel. Enter the resistance value of each resistor and get the total equivalent resistance instantly.

What Is a Parallel Resistor?

When two or more resistors are connected in parallel, each resistor is connected across the same two points in a circuit. The current divides between the different branches, while the voltage across each resistor remains the same.

The equivalent resistance of resistors connected in parallel is calculated using the reciprocal formula:

1/Rₜ = 1/R₁ + 1/R₂ + 1/R₃ + … + 1/Rₙ

For two resistors, the formula can also be written as:

Rₜ = (R₁ × R₂) / (R₁ + R₂)

How to Use the Parallel Resistor Calculator

  1. Enter the resistance value for the first resistor.
  2. Select the appropriate unit: Ω, kΩ, or MΩ.
  3. Add additional resistors as needed.
  4. Enter the value of each resistor.
  5. The calculator automatically calculates the equivalent resistance.

Parallel Resistor Formula

The general formula for calculating the equivalent resistance of resistors connected in parallel is:

1/Rₜ = 1/R₁ + 1/R₂ + 1/R₃ + … + 1/Rₙ

Where:

  • Rₜ = Equivalent or total resistance
  • R₁, R₂, R₃… = Individual resistor values
  • n = Number of resistors

Example

Suppose three resistors are connected in parallel:

  • R₁ = 100 Ω
  • R₂ = 200 Ω
  • R₃ = 300 Ω

The equivalent resistance is:

1/Rₜ = 1/100 + 1/200 + 1/300

Rₜ ≈ 54.55 Ω

Important Property of Parallel Resistors

The equivalent resistance of resistors connected in parallel is always less than the smallest individual resistance.

For example, if the smallest resistor in a parallel network is 100 Ω, the equivalent resistance will be less than 100 Ω.

Features

  • Calculate equivalent resistance instantly
  • Add multiple resistors
  • Supports Ω, kΩ, and MΩ
  • Automatically updates the result
  • Remove individual resistors
  • Simple and easy-to-use interface
  • Fully responsive on mobile, tablet, and desktop

Applications

A parallel resistor calculator can be useful for:

  • Electronics projects
  • Circuit design
  • Electrical engineering
  • Electronics students
  • Resistor network calculations
  • Learning parallel circuits
  • Checking manual calculations
  • Designing electrical circuits