Series Parallel Resistor Calculator
Calculate the total resistance of resistors in series and parallel configurations.
Series Resistor Calculator
Parallel Resistor Calculator
Understanding Resistor Configurations
Resistors can be connected in series or parallel to achieve a desired total resistance. Understanding these configurations is fundamental to circuit design.
Resistors in Series
When resistors are connected in series, the current flows through each resistor sequentially. The total resistance is simply the sum of the individual resistances.
Resistors in Parallel
When resistors are connected in parallel, they are connected across the same two points, meaning the voltage across each resistor is the same. The reciprocal of the total resistance is the sum of the reciprocals of the individual resistances.
or for two resistors:
Rtotal = (R1 × R2) / (R1 + R2)
Key Differences
| Feature | Series Circuit | Parallel Circuit |
|---|---|---|
| Current | Same through each resistor | Divides among branches |
| Voltage | Divides across each resistor | Same across each resistor |
| Total Resistance | Increases (sum of individuals) | Decreases (less than smallest individual) |
| Adding Resistors | Increases total resistance | Decreases total resistance |
Frequently Asked Questions
Why would I use resistors in series or parallel?
Resistors are combined to achieve a specific resistance value not readily available, to increase power dissipation capability, or to divide voltage or current within a circuit.
What is the 'product over sum' rule?
The 'product over sum' rule (R_total = (R1 × R2) / (R1 + R2)) is a shortcut formula specifically for calculating the total resistance of two resistors connected in parallel.