The International Tennis Federation has 7 different ball specifications (maybe 8 depending on how you count), each to be used for specific purposes/conditions. Of those, there are 5 different ball sizes. And then you’ve got all those various novelty balls that are not intended for actually playing tennis.
Do you know exact size of any of these balls?
When you do envelope calculations in software you never know precise values. But still these calculations can be useful.
Pages 5 and 6. Of course, it is a range for each size, not an exact measurement.