Parallel Resistor Calculator

In a parallel circuit, all resistors share the same voltage across their terminals. The total resistance is found from the reciprocal rule: 1/Rtotal = 1/R1 + 1/R2 + ... + 1/Rn. The result is always less than the smallest resistor in the network.

Current splits between parallel branches inversely proportional to resistance — a smaller resistor carries more current. This is exploited in current-sharing circuits, where multiple resistors (or transistors) share a high current to reduce per-component stress.

The two-resistor shortcut R1×R2/(R1+R2) is fast for hand calculations. For more resistors, either add them one pair at a time, or use the reciprocal sum directly. This calculator handles up to 5 resistors in parallel and also shows branch currents when a supply voltage is given.

Key Points

• Rtotal < min(R1, R2, ..., Rn) — always smaller than any single resistor
• Two resistors: Rtotal = R1×R2/(R1+R2)
• Each branch carries V/Rn — smaller R gets more current
• Equal resistors: Rtotal = R/n (n resistors in parallel)

Applications

• Achieving non-standard resistance values
• Current sharing in power circuits
• Low-impedance voltage dividers
• Parallel LED current distribution