Welcome to the forum, mastertask.
While I concur with NetNathan, let's take it one step further. Looking at a Rockwell Logix based processor, for example, a single BOOL tag by itself takes up 4 bytes of memory, the same as a singe DINT tag. If you're concerned about memory, using the individual bits within a DINT gives 32x more True/False memory tags than a single BOOL.
Since you didn't mention a specific processor, it's impossible to give a specific answer. It's always helps others help you to give more info than less.