The lowercase "s" is only 4 px tall. The "f" and "y" add 2 px above and below, so the total reserved height must be 8px. Then 2 more px for whitespace, so 10.
Weird that the lowercase letters with ascenders are taller than normal uppercase, I didn't notice that. But yeah, the core numbers+uppercase box is 3x5 (with only "Q" violating that). And it's all on a 4x8 grid.
