Is 1/2" drywall really 1/2"?

Fixing some ceiling drywall in my basement and noticed that the drywall was thinner in the ceiling than a wall I took down.

The ceiling drywall measures 7/16", however a quick search on this measurement seems to state that 1/2" drywall's actual measurement is 7/16".

Is 1/2" the drywall I need? Or is there such thing as 7/16" drywall?

Thanks!