milli-g
A thousandth of the acceleration due to gravity; 1 g is 1000 mg.
The milli-g (mg) is 10^-3 g, about 0.0098 m/s²; accelerometer readings in whole milli-g need no fractional part for typical vibration work.
Examples
The fan's accelerometer reports whole milli-g, so 1 g is 1000 and a housing at rest reads about 1000 mg on its vertical axis.
Readings in whole milli-g need no fraction bits: 0.98 g is simply the integer 980.
See also