Total Resistance $ R_{total} $:

0 Ω

Note on Calculation Results

This tool calculates theoretical values under ideal conditions. In actual circuits, values will vary due to resistor tolerance, wire resistance, contact resistance, and temperature changes.
For complex parallel circuit combinations, extremely minor errors may occur due to floating-point arithmetic.
We assume no responsibility for any damages caused by the results of this tool. Always verify with multiple methods for critical applications.

What is the Equivalent Resistance Calculator?

This calculator is an online tool that allows you to simulate the equivalent resistance of complex electrical circuits by freely combining series and parallel components. You can intuitively add resistors while looking at the diagram, and the calculation formula based on Ohm's Law is displayed in real-time.

Key Features

Visual Interface: Understand at a glance whether resistors are in series or parallel by looking at the diagram.
Detailed Formulas: Check the calculation process with beautiful mathematical expressions powered by MathJax.
Unit Support: Automatically converts and calculates not just Ω (Ohms), but also kΩ (Kilohms) and MΩ (Megohms).
Safe Design: Data is processed within your browser; entered values are never stored on external servers.

How to Use

Click to select the initial resistor (R1) displayed (a blue border will appear).
Press "Add Series" or "Add Parallel" to insert a new resistor.
Enter values in the input field of each resistor and select the unit (Ω/k/M) from the dropdown if necessary.
To remove an unwanted resistor, select it and click "Delete Selected."

Theory of Equivalent Resistance

Series Circuit Formula

In a series circuit, the total resistance is found by simply adding up the values of each resistor.

$$R = R_1 + R_2 + R_3 + \dots$$

Parallel Circuit Formula

In a parallel circuit, the equivalent resistance is the reciprocal of the sum of the reciprocals of each resistance.

$$R = \frac{1}{\frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + \dots}$$

FAQ

Q. Is there a limit to the number of resistors?

A. There is no theoretical limit, but we recommend staying within a range that is easy to manage on your screen size. It is mobile-friendly.

Q. Can I mix different units in calculations?

A. Yes. For example, if you put 100Ω and 1kΩ in parallel, the tool automatically unifies them to the base unit (Ω) for accurate calculation.

Q. Is there a fee to use this?

A. No, all tools on this site are provided for free. Operations are supported by advertising revenue, so there are no additional costs.