Resistor Series & Parallel Calculator
Total resistance of any list of resistors in series or parallel — understands 4.7k, 2k2 and 0R47 shorthand.
Resistor Series & Parallel Calculator computes the combined resistance of any list of resistors in series or parallel — free, instant and private in your browser. Students learning Kirchhoff and engineers improvising values from the parts drawer use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About Resistor Series & Parallel Calculator
Resistor Series & Parallel Calculator computes the combined resistance of any list of resistors in series or parallel using the standard engineering relation: series: R = ΣRi; parallel: 1/R = Σ(1/Ri). Worked live: 4.7 kΩ ∥ 10 kΩ ∥ 22 kΩ combines to about 2.9 kΩ. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use Resistor Series & Parallel Calculator
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use Resistor Series & Parallel Calculator?
- ✓Implements the real formula — series: R = ΣRi — with the substitution shown, not a black box
- ✓Built for students learning Kirchhoff and engineers improvising values from the parts drawer
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate resistor series & parallel?+
The combined resistance of any list of resistors in series or parallel follows series: R = ΣRi; parallel: 1/R = Σ(1/Ri). For example, 4.7 kΩ ∥ 10 kΩ ∥ 22 kΩ combines to about 2.9 kΩ. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Why do two equal resistors in parallel halve the resistance?+
Each path carries equal current, so the pair conducts twice as well as one — conductances add in parallel. Bonus: the combination also has twice the power rating and slightly better tolerance statistics, a standard trick for power shunts.
What happens to tolerance when I combine resistors?+
The combined value's tolerance stays roughly the same percentage as the parts (it does not add). Statistically, independent errors partially cancel, so a series/parallel pair of ±5 % parts is usually a bit better than ±5 % — but never count on it for design margin.
Is the Resistor Series & Parallel Calculator free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
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