Resistor Calculator
Combine resistors, capacitors or inductors in series or parallel with the correct rule for each component type.
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What this tool does
Combine resistors, capacitors or inductors in series or parallel with the correct rule for each component type. Components are ideal and, for inductors, uncoupled. Enter every value in the same unit (ohms, µF or mH) — the equivalent is returned in that unit.
How to use the Resistor Calculator
- Enter or select combination mode.
- Enter or select value 1 (ω, µf or mh by mode).
- Enter or select value 2 (ω, µf or mh by mode).
- Enter or select value 3 (0 = unused).
- Read the calculated result; change any measurement to compare alternatives.
Formula
series-type (R series, L series, C parallel): sum; reciprocal-type (R parallel, L parallel, C series): 1 ÷ Σ(1/value)
- mode
- Combination mode
- v1
- Value 1 (Ω, µF or mH by mode)
- v2
- Value 2 (Ω, µF or mH by mode)
- v3
- Value 3 (0 = unused)
Components are ideal and, for inductors, uncoupled. Enter every value in the same unit (ohms, µF or mH) — the equivalent is returned in that unit.
Worked example
For resistor calculator, the following measurements illustrate the exact method: Combination mode: rpar; Value 1 (Ω, µF or mH by mode): 100; Value 2 (Ω, µF or mH by mode): 200; Value 3 (0 = unused): 300.
Inputs
- Combination modeResistors in parallel
- Value 1 (Ω, µF or mH by mode)100
- Value 2 (Ω, µF or mH by mode)200
- Value 3 (0 = unused)300
Result
- Equivalent value54.55
- Series sum of values600
- Parallel equivalent of values54.55
- Components combined3
Results explained
- Equivalent value
- Equivalent value from the formula above. Components are ideal and, for inductors, uncoupled. Enter every value in the same unit (ohms, µF or mH) — the equivalent is returned in that unit.
- Series sum of values
- Series sum of values from the formula above. Components are ideal and, for inductors, uncoupled. Enter every value in the same unit (ohms, µF or mH) — the equivalent is returned in that unit.
- Parallel equivalent of values
- Parallel equivalent of values from the formula above. Components are ideal and, for inductors, uncoupled. Enter every value in the same unit (ohms, µF or mH) — the equivalent is returned in that unit.
- Components combined
- Components combined from the formula above. Components are ideal and, for inductors, uncoupled. Enter every value in the same unit (ohms, µF or mH) — the equivalent is returned in that unit.
Frequently asked questions
Reciprocally: 1/Req = 1/R1 + 1/R2 + 1/R3. Two equal resistors in parallel give half of one resistor, and the equivalent is always smaller than the smallest branch.
They simply add: Req = R1 + R2 + R3. Series resistance is always larger than the largest single resistor.
No — capacitors are the mirror image: capacitors in parallel add like series resistors, and capacitors in series combine reciprocally like parallel resistors.
Uncoupled inductors follow the resistor rules: series inductors add, parallel inductors combine reciprocally. Mutual inductance between coupled coils is not modelled here.
Zero-valued fields are treated as unused and ignored, so you can combine two components by leaving the third at 0.