Parallel resistance calculator
When resistors are connected in parallel, they share the same voltage and the current splits between them, so the network conducts more easily than any single resistor. This calculator takes any list of resistor values and returns the equivalent (total) resistance — the single resistor that would behave the same. Handy for electronics design, circuit homework and quickly checking a resistor combination.
How it works
The tool reads your comma- or space-separated values, keeps the positive ones, and applies the reciprocal rule:
1/Rt = 1/R1 + 1/R2 + ... + 1/Rn
Rt = 1 ÷ (sum of reciprocals)It sums each resistor’s reciprocal (its conductance), then inverts that sum. The result is always less than the smallest resistor in the list, because every added path gives current somewhere else to flow.
Example
Three resistors of 100 Ω, 220 Ω and 470 Ω in parallel:
- 1/100 + 1/220 + 1/470 = 0.01 + 0.004545 + 0.002128 = 0.016673 S
- Rt = 1 ÷ 0.016673 ≈ 59.98 Ω
| Resistors (Ω) | Equivalent (Ω) |
|---|---|
| 100, 100 | 50 |
| 100, 220, 470 | 59.98 |
| 1000, 1000, 1000 | 333.33 |
Every calculation happens in your browser — nothing is uploaded.