I have a Garmin Lily. It records an accurate number of steps through out the day. However the distance vary even though the steps do not.
Example: One day 10,114 steps = 4.9 miles. Then the next day 10,112 steps = 5.7 miles.
This happens regularly. I have not noticed a pattern. This is just walking around a classroom while teaching. Not during runs or hiking.
Sorry if this has been discussed. I searched a few different times and couldn't find anything that seemed to match.