Parallel Resistance Calculator

Combine two resistors in parallel — the total is always less than the smaller one.

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Total resistance50.000Ω
In kilohms0.0500kΩ

For two resistors in parallel the reciprocals add: 1 / R_total = 1 / R1 + 1 / R2, which rearranges to R_total = (R1 × R2) ÷ (R1 + R2). Two 100 Ω resistors in parallel give 1 ÷ (1/100 + 1/100) = 50 Ω. The combined value is always smaller than the smallest resistor, because the current now has more than one path to flow through.

Questions

How do I calculate parallel resistance?
Add the reciprocals and invert: 1 / R_total = 1 / R1 + 1 / R2, or R_total = (R1 × R2) ÷ (R1 + R2). Two 100 Ω resistors in parallel give 50 Ω.
Why is parallel resistance lower than each resistor?
Parallel resistors give current extra paths to flow through, so the combined resistance is always less than the smallest individual resistor.