Wheatstone Bridge Calculator

Free Wheatstone Bridge Calculator — solve balanced and unbalanced four-resistor bridges for unknown resistance or output voltage.

866.9K uses Updated · 2026-05-11 Runs locally · zero upload
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The Wheatstone Bridge Calculator handles both balanced bridges (find an unknown resistance) and unbalanced bridges (find the differential output voltage).

How to Use Wheatstone Bridge Calculator

  1. Pick a mode — Balanced (solve unknown) or Unbalanced (compute Vout).
  2. Enter the resistors — R1, R2, R3 and (optionally) R4 / unknown.
  3. Enter the excitation voltage — only needed for the unbalanced mode.
  4. Read the answer — unknown resistance in balanced mode, or Vout and balance flag in unbalanced mode.

Formula & Theory — Wheatstone Bridge Calculator

Balance condition:  R1 / R2 = R3 / R4
Unknown:  Rx = R3 · R2 / R1
Unbalanced output:  Vout = Vs · ( R2/(R1+R2) − R4/(R3+R4) )

Use Cases for Wheatstone Bridge Calculator

  • Strain gauges — convert resistive strain into a measurable voltage.
  • Temperature sensing — interface RTDs and thermistors.
  • Precision resistance measurement — verify a resistor against three known references.
  • Education — explore the symmetry of the bridge condition.

Frequently asked questions about Wheatstone Bridge Calculator

When is a bridge perfectly balanced?

When the ratio R1/R2 equals R3/R4. At this point the differential output Vout is zero regardless of the supply voltage.

Why use a bridge instead of a single resistor?

A bridge rejects common-mode drifts (such as supply voltage variations) and provides a differential output that is easy to amplify.

What if the bridge is far from balance?

The output becomes a nonlinear function of the unknown resistance; calibration tables or curve fitting are then required.

Is my data stored?

No. All calculations run locally in your browser; nothing is sent to any server.