Resistors in Series and Parallel Calculator
Type your resistor values, one per line or separated by commas, and choose series or parallel. You get the total resistance for both connections.
- Nothing you type is stored
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Series total
5.02 kΩ
- Parallel total
- 67.76 Ω
- Resistors
- 3
Series: R = R1 + R2 + …
Show working
- R = 100 Ω + 220 Ω + 4.7 kΩ = 5.02 kΩ
How to use
- Type resistor values, one per line (k = kilo, M = mega, 4k7 = 4.7 kΩ).
- Choose series or parallel.
- Read the total and the working.
Good to know
Series: R = R1 + R2 + R3 … (the same current flows through each). Parallel: 1/R = 1/R1 + 1/R2 + 1/R3 … (the same voltage across each), so the total is always smaller than the smallest resistor.
Two equal resistors in parallel give half the value; two in series give double. Shortcut for two in parallel: R = R1 × R2 ÷ (R1 + R2).
Values: 220, 4.7k or 4k7 (4,700 Ω), 1M (1,000,000 Ω); a small m means milli (0.001). Real resistors have tolerance (often ±5%), so the measured total varies by the same order.
Questions
What is 100 Ω and 220 Ω in parallel?
100 × 220 ÷ 320 = 68.75 Ω.
How do I make 50 Ω from 100 Ω resistors?
Put two 100 Ω resistors in parallel.
Is parallel resistance always lower?
Yes, it is always below the smallest resistor in the group.
How do I type 4.7 kΩ?
4.7k or 4k7. Mega-ohms use capital M, e.g. 1M.
Can I mix series and parallel?
Work it in steps: find each parallel group, then add groups in series.