We always complain there is no pythagorean theorem in D&D. Well, we have the technology . . . . Note-this does not change the Glide mechanic that Birdfolk have.
Because I'm (mostly) rounding down, it creates odd looking sets of numbers. If you want to double check the math, it's in the second tab. Still, it gives you much more movement than the usual way we try and figure it out. (Only horizontal and vertical, no diagonal.)
Basically, for each row you pick one number for your horizontal movement and the other number becomes your vertical movement. For a fly speed of 30, you could go forward 5 and up 25. Or, forward 25 and up 5.