Parallel Resistors Calculator
Calculate total resistance for parallel resistors.
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Enter up to five resistance values in ohms. Leave unused fields blank. The calculator shows the total equivalent parallel resistance instantly.
About Parallel Resistors
When resistors are connected in parallel, they share the same voltage but the current divides among them. The total resistance is always less than the smallest individual resistor. The formula 1/Rt = 1/R1 + 1/R2 + ... follows from Kirchhoff's current law and Ohm's law. Parallel resistor networks are ubiquitous in electronics for current division, voltage regulation, and impedance matching.
Frequently Asked Questions
How do resistors combine in parallel?
In parallel, the reciprocal of total resistance equals the sum of reciprocals: 1/Rt = 1/R1 + 1/R2 + ... The total is always less than the smallest individual resistor.
Why is parallel resistance lower than any single resistor?
Parallel paths give current more routes to flow. More paths mean less total resistance, just like adding lanes to a highway reduces congestion.
What is the shortcut for two parallel resistors?
For exactly two resistors: Rt = (R1 x R2) / (R1 + R2). This product-over-sum formula is a quick way to calculate two parallel resistors.