🔬 Wheatstone Bridge Calculator
Find the unknown resistance in a balanced Wheatstone bridge from the three known resistors.
What this calculator does
A Wheatstone bridge is a classic circuit used to precisely measure an unknown resistance by balancing it against three known resistors, so that no current flows through a galvanometer connecting the bridge’s midpoints.
The formula
At balance, the ratio of resistors in one branch equals the ratio in the other: R1 / R2 = R3 / Rx, which rearranges to Rx = (R2 × R3) / R1. R1 and R2 are typically the fixed ratio arms, while R3 is a known, adjustable resistor tuned until the bridge balances (zero galvanometer deflection).
This calculator assumes an ideally balanced bridge with negligible wire resistance and contact resistance. It is intended for general electronics education and lab work.