Resistor Calculator
Calculate total resistance for series and parallel resistor combinations. Enter 2–10 resistor values.
Enter at least 2 resistor values.
Series and Parallel Formulas
Series: R_total = R₁ + R₂ + R₃ + ...
Parallel: 1/R_total = 1/R₁ + 1/R₂ + 1/R₃ + ...
Parallel: 1/R_total = 1/R₁ + 1/R₂ + 1/R₃ + ...
In series, total resistance increases. In parallel, total resistance is always less than the smallest resistor.
Example: 100Ω, 200Ω, 300Ω
Series = 600Ω | Parallel = 54.55Ω
Series = 600Ω | Parallel = 54.55Ω
FAQ
When do I use series vs parallel?
Series: increases total resistance (voltage dividers). Parallel: decreases total resistance, increases current capacity, provides redundancy.
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Last updated: 2026-08-08