Resistors in Parallel Calculator – Total Resistance
Calculate total resistance for parallel resistors
Table of Contents
How to Use
- Enter at least two resistor values in ohms
- Optionally add up to 6 resistors total
- Click calculate to see the total equivalent resistance
- The result will always be less than the smallest resistor
What are Parallel Resistors?
Resistors are connected in parallel when both ends of each resistor are connected to the same two points. In a parallel circuit, the voltage across each resistor is the same, but the current splits between the resistors.
The total equivalent resistance of parallel resistors is always less than the smallest individual resistor value. This is because adding parallel paths provides more routes for current to flow.
Parallel Resistance Formula
The formula for total resistance in parallel is:
- 1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn
- Or: Rtotal = 1 / (1/R1 + 1/R2 + 1/R3 + ... + 1/Rn)
- For two resistors: Rtotal = (R1 × R2) / (R1 + R2)
For identical resistors in parallel, the total resistance equals the value of one resistor divided by the number of resistors.
Common Applications
- Reducing total resistance in a circuit
- Creating specific resistance values from standard resistors
- Current divider circuits
- Increasing power handling capability
- Redundancy in critical circuits
- Load sharing in power supplies
Frequently Asked Questions
- Why is parallel resistance always less than the smallest resistor?
- Because adding resistors in parallel provides additional paths for current to flow. More paths mean less total opposition to current, resulting in lower total resistance.
- What happens if I have two equal resistors in parallel?
- The total resistance will be exactly half of one resistor's value. For example, two 100Ω resistors in parallel give 50Ω total resistance.
- How do I calculate parallel resistance for just two resistors?
- Use the product-over-sum formula: Rtotal = (R1 × R2) / (R1 + R2). This is faster than the reciprocal formula for two resistors.
- Can I mix different resistor values in parallel?
- Yes, you can connect any combination of resistor values in parallel. The calculator handles different values using the reciprocal formula.
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