Strain Gauge Resistance Change

ΔR = R × GF × ε

Quick answer

This calculator solves ΔR = R × GF × ε for Resistance Change. With Nominal Resistance 0.47 kΩ, Gauge Factor 0.5, Strain (µε) 1.1, the result is 0.2585 mΩ. It solves in 4 directions, so you can enter the values you have and get the one you need.

Calculator

Resistance Change (mΩ)
—

Formula

ΔR = R × GF × ε

Description

A strain gauge changes resistance proportionally to the mechanical strain applied to it. The gauge factor (GF) is the sensitivity: the ratio of fractional resistance change to strain. Metal foil gauges have GF ≈ 2, meaning 1 microstrain (1 µε = 1 ppm elongation) causes a 2 ppm resistance change. For a 350Ω gauge at 1000 µε, ΔR is only 0.7Ω, which is why Wheatstone bridges and precision instrumentation amplifiers are required for measurement. Semiconductor strain gauges have GF of 100-200 but are more temperature-sensitive.

Variables

  • ΔR — Resistance change (Ω)
  • R — Nominal gauge resistance (Ω)
  • GF — Gauge factor (dimensionless)
  • ε — Mechanical strain in microstrain (µε)

Practical Notes

Standard gauge resistances: 120Ω, 350Ω, 1000Ω. Higher resistance reduces self-heating and lead wire errors. The strain value entered is in microstrain (µε) and is automatically scaled by 1e-6 internally. Temperature compensation is achieved using dummy gauges or self-compensating gauge alloys. Load cells use multiple strain gauges in a full Wheatstone bridge for maximum sensitivity.

Symbols and units

Symbol Meaning Default unit Accepted units
dR Resistance Change mΩ mΩ, Ω, kΩ, MΩ
R Nominal Resistance Ω mΩ, Ω, kΩ, MΩ
GF Gauge Factor — —
epsilon Strain (µε) — —

Step by step

  1. 1. What you know: Nominal Resistance 0.47 kΩ, Gauge Factor 0.5, Strain (µε) 1.1
  2. 2. The relation: ΔR = R × GF × ε
  3. 3. Substitute: R = 0.47 kΩ, GF = 0.5, epsilon = 1.1
  4. 4. Result: Resistance Change = 0.2585 mΩ

Nearest standard component values

Series Nearest value Error
E12 0.27 mΩ 4.4%
E24 0.27 mΩ 4.4%

Worked examples

Minimum range

Given: Nominal Resistance 1 Ω, Gauge Factor 0.025, Strain (µε) 0.055

Result: Resistance Change = 1.38 × 10⁻⁶ mΩ

Low range

Given: Nominal Resistance 10 Ω, Gauge Factor 0.25, Strain (µε) 0.55

Result: Resistance Change = 0.001375 mΩ

Typical

Given: Nominal Resistance 0.47 kΩ, Gauge Factor 0.5, Strain (µε) 1.1

Result: Resistance Change = 0.2585 mΩ

High range

Given: Nominal Resistance 4.7 kΩ, Gauge Factor 0.8, Strain (µε) 1.76

Result: Resistance Change = 6.618 mΩ

Maximum range

Given: Nominal Resistance 47 kΩ, Gauge Factor 8, Strain (µε) 17.6

Result: Resistance Change = 6.618 Ω

Solving for each variable

Solve for Resistance Change

Nominal Resistance 1 Ω, Gauge Factor 0.025, Strain (µε) 0.055 → 1.38 × 10⁻⁶ mΩ

Solve for Nominal Resistance

Resistance Change 0.1 mΩ, Gauge Factor 0.025, Strain (µε) 0.055 → 72.73 kΩ

Solve for Gauge Factor

Resistance Change 0.1 mΩ, Nominal Resistance 1 Ω, Strain (µε) 0.055 → 1818

Solve for Strain (µε)

Resistance Change 0.1 mΩ, Nominal Resistance 1 Ω, Gauge Factor 0.025 → 4000

How Resistance Change changes with Nominal Resistance

Nominal Resistance (input) Resistance Change (result)
47 Ω 0.02585 mΩ
117.5 Ω 0.06463 mΩ
0.235 kΩ 0.1293 mΩ
0.3525 kΩ 0.1939 mΩ
0.47 kΩ 0.2585 mΩ
0.705 kΩ 0.3878 mΩ
0.94 kΩ 0.517 mΩ
1.88 kΩ 1.034 mΩ
3.29 kΩ 1.81 mΩ
4.7 kΩ 2.585 mΩ

The same result in other units

Unit Value
mΩ 0.2585
Ω 0.0002585

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Frequently asked questions

How do you calculate Strain Gauge Resistance Change?

Use ΔR = R × GF × ε. With Nominal Resistance 0.47 kΩ, Gauge Factor 0.5, Strain (µε) 1.1, Resistance Change works out to 0.2585 mΩ.

How do you calculate change in resistance with strain?

Rearrange for Resistance Change: with Nominal Resistance 10 Ω, Gauge Factor 0.25, Strain (µε) 0.55, Resistance Change is 0.001375 mΩ.

How do you calculate strain from resistance r1 sensitivity factor 2?

Rearrange for Resistance Change: with Nominal Resistance 0.47 kΩ, Gauge Factor 0.5, Strain (µε) 1.1, Resistance Change is 0.2585 mΩ.

What is the formula for Strain Gauge Resistance Change?

The formula is ΔR = R × GF × ε. A strain gauge changes resistance proportionally to the mechanical strain applied to it.

How do you find Nominal Resistance when you know the other values?

Rearrange for Nominal Resistance: with Resistance Change 0.1 mΩ, Gauge Factor 0.025, Strain (µε) 0.055, Nominal Resistance is 72.73 kΩ.

How do you find Gauge Factor when you know the other values?

Rearrange for Gauge Factor: with Resistance Change 0.1 mΩ, Nominal Resistance 1 Ω, Strain (µε) 0.055, Gauge Factor is 1818.

Related Concepts

All Sensors & ADC formulas →
ADC Resolution (LSB) ADC Theoretical SNR Steinhart-Hart Temperature Wheatstone Bridge Linear Sensor Transfer Function Oversampling SNR Improvement RTD Callendar-Van Dusen Strain Gauge Resistance Change

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