How to use the parallel resistor calculator
- Choose resistors, capacitors or inductors and enter one value per line.
- Parallel and series totals appear together.
- To make a non-standard value, enter the resistor you have and the value you want.
Two resistors in parallel and in series
Series total = R1 + R2 + …; parallel total = 1 ÷ (1/R1 + 1/R2 + …), and for two resistors R1 × R2 ÷ (R1 + R2). A parallel result is always below the smallest resistor. Capacitors work the other way round: parallel values add, series values combine as reciprocals.
| Pair | Parallel | Series |
|---|---|---|
| 100 Ω ∥ 100 Ω | 50 Ω | 200 Ω |
| 1 kΩ ∥ 1 kΩ | 500 Ω | 2 kΩ |
| 1 kΩ ∥ 2.2 kΩ | 688 Ω | 3.2 kΩ |
| 1 kΩ ∥ 4.7 kΩ | 825 Ω | 5.7 kΩ |
| 4.7 kΩ ∥ 4.7 kΩ | 2.35 kΩ | 9.4 kΩ |
| 10 kΩ ∥ 10 kΩ | 5 kΩ | 20 kΩ |
| 10 kΩ ∥ 22 kΩ | 6.88 kΩ | 32 kΩ |
| 10 kΩ ∥ 47 kΩ | 8.25 kΩ | 57 kΩ |
| 22 kΩ ∥ 33 kΩ | 13.2 kΩ | 55 kΩ |
| 100 kΩ ∥ 100 kΩ | 50 kΩ | 200 kΩ |
Frequently asked questions
How do you calculate resistors in parallel?
Parallel total = 1 ÷ (1/R1 + 1/R2 + …). For two resistors use R1 × R2 ÷ (R1 + R2); two equal resistors give half the value.
How is power shared in parallel?
Parallel resistors share the same voltage, so each dissipates V² ÷ R and the smaller resistor takes more. In series the current is shared and each dissipates I² × R.
How do capacitors add up?
The opposite of resistors: capacitors in parallel add, in series they combine as reciprocals. Inductors behave like resistors when there is no mutual coupling. Switch the component type above.
Are my inputs uploaded?
No. Everything is calculated locally in your browser and nothing is stored; a share link only carries the values you entered.
Results are for design estimates and part selection; for production and safety-related circuits follow component datasheets, applicable standards and measurements.