# Test and Measurement World

## Test and Measurement World Terminology Section

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## Gauge Factor used in Strain Gauge | What is Gauge Factor

This page describes Gauge factor definition used in Strain Gauge. It also mentions Gauge Factor equation.

The term Gauge Factor is associated with Strain Gauge. The strain Gauge is basically a passive transducer. It converts mechanical displacement into change in the resistance. It is a thin wafer type device which can be attached with variety of materials in order to measure the applied strain.

The change in resistance is proportional to applied strain. It is measured with wheatstone bridge structure.

Definition: The Sensitivity of Strain Gauge can be described in terms of Gauge factor. The Gauge factor is the ratio of change in resistance to change in length. It is expressed as follows.

### Strain Gauge Factor Equation

Following is the equation of strain Gauge factor. Where, K = Gauge Factor
R = Nominal Gauge Resistance
ΔR = Change in Gauge Resitance
L = Normal specimen length in unstressed condition
ΔL = change in specimen length

Strain in the lateral direction can be expressed as,
σ = ΔL/L