μm/m\mu\text{m/m}

microstrain

Strainexact by definition

One micrometre of extension per metre of length: microstrain, written µε. It equals one part per million, and it is what strain gauges read.

1 μm/m\mu\text{m/m} 0.000001 m/m\text{m/m}
Where the unit came from

A foil strain gauge resolves about one microstrain, and working strains in steel and concrete run from tens to a few thousand of them, so the unit was chosen to make the instrument's output a readable whole number. Yield in mild steel is roughly 1200 µε.

One microstrain in every strain unit

0.000001meter per meter (m/m)
0.000001inch per inch (in/in)
1microstrain (µm/m)this unit
0.001millimeter per meter (mm/m)
0.001mil per inch (mil/in)
0.0001percent strain (%)