It depends what kind of gauge you have.
Most will only measure the amount of paint from the surface to the metal.
You can't tell what is clear coat and what is base coat/primer.
Generally anything below 85uM I would be very cautious of and only use very light polishes, anything below 80 I would not touch at all. As a rough estimate it's about 30-35% each. So if you have a panel with 120uM on it, as a rough estimate around 40uM of that will be clearcoat.
In paint correction terms you are only interested in how much clear coat you have.
You can buy gauges which measure remaining clear coat, they can display individual levels, but I've never used one of those, plus they cost about £4k. Not worth it.