Parallel Resistance Calculator

Summary

Calculate the total equivalent resistance of two or more resistors connected in parallel using the reciprocal formula.

How it works

1. Enter the value of each resistor in ohms (Ω), kilohms (kΩ), or megaohms (MΩ) using the unit selector.
2. Click "Add Resistor" to add more rows — up to 10 resistors are supported.
3. The equivalent resistance is recalculated automatically as you type.
4. The tool applies the reciprocal formula: 1/R_total = 1/R1 + 1/R2 + ... + 1/Rn.
5. Results are displayed in the most readable unit (Ω, kΩ, or MΩ).
6. Remove any row with the × button; at least two resistors are required.

Use cases

• Finding the equivalent resistance of parallel branches in a PCB design.
• Calculating the combined load seen by a power supply with multiple parallel resistors.
• Teaching Ohm's Law and parallel circuit theory.
• Quickly verifying hand calculations during circuit troubleshooting.
• Designing current-sharing networks where identical resistors split current evenly.
• Checking the Thevenin equivalent resistance of a parallel resistor network.

Frequently Asked Questions