Series and parallel resistor calculator
Type the values separated by commas, spaces or new lines, then choose the connection type.
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How to use it
- Enter connection and resistor values in ohms.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Series: R = R1 + R2 + R3. Parallel: 1 ÷ R = 1 ÷ R1 + 1 ÷ R2 + 1 ÷ R3, for as many resistors as you list.
Example
Inputs: Connection = Parallel. Result: Equivalent resistance: 56.8966 Ω; Short form: 56.8966 Ω; Number of resistors: 3.
Limits and caveats
- For mixed networks (series inside parallel), work in steps: combine each branch first, then combine the branches.
- The suffix k means thousand and M means million; forms like 4k7 are not accepted.
Questions about this tool
Why is parallel resistance smaller than the smallest resistor?
Each extra branch opens another path for current, so the total opposition drops.
What do two equal resistors in parallel give?
Half of one of them. Two 100 Ω resistors in parallel give 50 Ω.
Can I enter kilohms?
Yes, type 4.7k or 1M, or type the full value in ohms.