Free online calculator

Wheatstone bridge calculator

Example Vout = 0 V — for balance (Vout = 0), Rx would need to be 1 kΩ

Example Bridge is currently balanced.

Each half is its own divider, and the output is the difference between their midpoints: $V_{out} = V_{ex} \times (\frac{R_{2}}{R_{1} + R_{2}} - \frac{R_{x}}{R_{3} + R_{x}})$

The bridge is balanced — $V_{out} = 0$ — when $R_{1} \times R_{x} = R_{2} \times R_{3}$ , so an unknown resistance resolves to $R_{x} = \frac{R_{2} \times R_{3}}{R_{1}}$ . That is how strain gauges, load cells and RTDs are read against three known resistors.

What you enter

Excitation Vex (V)
R1 (Ω)
R2 (Ω)
R3 (Ω)
Rx — unknown/test (Ω)

More calculators

Resistor combination solverYou need a value the E-series does not stock. This finds the nearest standard resistor, and the best two-resistor series and parallel combinations from…
Resistor ratio— or with "Invert" ticked.
Star / delta transformSome networks — a Wheatstone bridge with a load across the middle is the standard one — have no two resistors in plain series or plain parallel, so the…
Thévenin / NortonAny linear source, however many parts are inside it, behaves at one pair of terminals exactly like a voltage source behind a series resistance — or, just…
Wire voltage drop, where for a round trip. The ohms per metre come from the AWG table.
Zener shunt regulatorA zener holds the output at by swallowing whatever current the load leaves behind, so the series resistor is sized by the worst corner and never by the…
AC voltage converterSine wave assumed. — —
ADC step converterWhat one count is worth, and how counts and volts map onto each other, using the common Arduino-sketch convention where full scale is the top count,…