Parallel Resistance Calculator
Calculate total resistance for resistors in parallel, from two or more values, with this free electronics calculator in your browser.
Enter Values
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How to use this calculator
- Enter the two resistor values.
- Press Calculate.
How it works
Two resistors in parallel = (R1 × R2) ÷ (R1 + R2). The total is always less than the smaller one.
Worked example
4 Ω and 4 Ω. = 2 Ω.
Common mistakes
- Adding resistors in parallel like series — parallel resistance is always less than the smallest resistor.
- Forgetting that equal resistors in parallel just divide by the count (two 100 Ω give 50 Ω).
Frequently asked questions
How do you calculate parallel resistance?
Add the reciprocals: 1/Rt = 1/R1 + 1/R2 + … then invert. The total is always smaller than the lowest individual resistor.
Why is parallel resistance lower?
Extra parallel paths give current more ways to flow, so overall opposition drops as you add resistors.
Why is parallel resistance lower than either resistor?
A parallel path gives current more ways to flow, so the combined resistance is always less than the smallest resistor.
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Cite this tool
Zerdly. (2026). Parallel Resistance Calculator. Retrieved from https://www.zerdly.com/tools/parallel-resistance-calculator/
Tip: Enter any known values to calculate the remaining results.
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