As you are being told, this will vary a little bit with the spring angle, the specific profile tips, even the manufacturer.
Some 7" crown is less than 7", some can be more than 7". There are a lot of variables.
But here are a few numbers you can put in the back of your head as ballpark figures..... as distances out onto the ceiling. Use the opposite numbers for wall hangdown.
38= about 4 3/8" You're pretty safe figuring 4 1/2"
45= about 5", give or take a quarter or so.
52= about 5 9/16" Somewhat safe at 5 5/8"
None of this is exact, it's all "give or take" a few fractions, so do like the others suggested, and get a little piece of EXACTLY the molding you intend to use, and measure it in place.