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Series / parallel resistors

Find the combined resistance of ideal resistors in series or parallel.

Ideal resistor arithmetic; component tolerance, temperature and power rating are separate checks.

Circuit topology

Series and parallel are different circuits. Choose one; the math matches that layout only.

Series (one path)

Resistors in order along the chain
R1
Ω
R2
Ω

Results

Choose topology, enter resistor values, then calculate.

Method and assumptions

Ideal resistors. Inputs: 0.0001 Ω to 1000000000000 Ω per field. Series sums R; parallel sums conductance 1/R.

Related calculators

Check the stated method and limits against your installation. Results are calculation aids, not certification.

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Calculation model 2026-11-02.1