Calculators
Series and Parallel Resistor Calculator
Calculate equivalent resistance for ideal resistors connected entirely in series or entirely in parallel, privately in your browser.
Enter 1–1000 positive resistances in one unit, separated by commas, semicolons, spaces, or newlines. Use values from 1e-12 to 1e12. Changing the unit reinterprets the numbers.
Combine resistances in a series or parallel group.
Series resistance is R = R₁ + R₂ + … + Rₙ. Parallel resistance follows 1/R = 1/R₁ + 1/R₂ + … + 1/Rₙ. For 10, 20, and 30 ohms, series resistance is 60 ohms and parallel resistance is approximately 5.45454545455 ohms. Series resistance is at least the largest resistance; parallel resistance is at most the smallest. A single resistor returns its own value. Enter 1 to 1000 positive values from 1e-12 to 1e12 in the selected unit, separated by commas, semicolons, spaces, or newlines. Scientific notation is accepted. Changing units reinterprets the numbers rather than converting them. Zero-ohm shorts and open circuits are excluded. This models ideal resistors in a single series or parallel group, excluding mixed networks, component tolerances, temperature changes, and power ratings. Results use up to 12 significant digits. All calculations stay in your browser.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
How do series and parallel resistance differ?
Series resistances add directly. Parallel resistance is the reciprocal of the sum of reciprocals. For 10, 20, and 30 ohms, the totals are 60 ohms in series and about 5.45454545455 ohms in parallel.
Can I mix resistance units?
Convert all values to the same unit first. Choose Ω, kΩ, MΩ, or mΩ for the entire group. Changing the unit reinterprets the entered numbers.
Can this solve mixed networks or determine power ratings?
No. This tool models one ideal series group or one ideal parallel group. It does not model mixed networks, tolerances, temperature effects, or power ratings. Zero-ohm shorts and open circuits are excluded.
Which inputs are supported?
Enter 1 to 1000 positive values from 1e-12 to 1e12 in the chosen unit. Separate them with commas, semicolons, spaces, or newlines. Scientific notation is supported; calculations stay in your browser and display up to 12 significant digits.