Case 1
- First resistance R1 (Ω)
- 4Ω
- Second resistance R2 (Ω)
- 4Ω
2.000Ω
Open with these valuesParallel Resistor Calculator
2.000Ω
Result: 2.000 ΩTwo resistors in parallel come out as product over sum: 4 Ω beside 4 Ω give 16 ÷ 8 = 2 Ω, always below the smaller one. A second path makes it easier for current to flow, not harder. Watch the mirror image — capacitors in parallel add instead of dividing.
Worked examples
Case 2
- First resistance R1 (Ω)
- 2Ω
- Second resistance R2 (Ω)
- 8Ω
1.600Ω
Open with these valuesCase 3
- First resistance R1 (Ω)
- 100Ω
- Second resistance R2 (Ω)
- 100Ω
50.000Ω
Open with these valuesHow it's calculated
Rp = (R1 × R2) ÷ (R1 + R2)
- StepEnter both resistances in ohms — a 4k7 resistor is 4700 Ω.
- StepMultiply the two values, then divide by their sum.
- ResultRead the total; it always falls below the smaller resistor.
Reference table
| R1 (Ω), R2 (Ω) | What it is | Parallel (Ω) |
|---|---|---|
| 2, 8 | an unequal pair | 1.6 |
| 4, 4 | the default pair | 2 |
| 6, 3 | unequal, same result | 2 |
| 10, 10 | two equal parts | 5 |
| 50, 50 | half of one | 25 |
| 100, 100 | half of one | 50 |
Questions
How do two resistors in parallel combine?
By the product-over-sum rule: Rp = (R1 × R2) ÷ (R1 + R2). For 4 Ω and 4 Ω that is 16 ÷ 8 = 2 Ω. Resistors are in parallel when they share the same two connection points, so the current can split between them.
Why is the parallel resistance smaller than either resistor?
Because a second path makes it easier for current to flow, not harder. With two routes the current splits, so the pair offers less resistance than the smaller part on its own. Two 4 Ω resistors in parallel give 2 Ω.
What happens when both resistors are equal?
The total is exactly half of one of them, because R times R over R plus R is R ÷ 2. Two 4 Ω resistors give 2 Ω and two 100 Ω resistors give 50 Ω.
How is parallel different from series?
It is the opposite. In series the resistors sit end to end and you simply add them, so the total grows. In parallel they share both ends and the total drops below the smaller one.
Where is parallel resistance used?
Sharing current between two parts so neither is overloaded, building a precise value from standard resistors on hand, and lowering the resistance of a load. It also tells you how current divides in a network. Any time two paths share the same two nodes, this rule applies.
Sources and last check
Information, not professional advice.