I have a small board designed with Altium, and when I upload the design, the website confirms the size is 2.925 x 1.175". After the bot has run, it claims the board is now 2.973895 x 1.365000. There’s no stray parts of the board outside the outline, and the outline is only 1mil thick. The height is pretty far off (16%).
Is it just rounding up to a specific weird grid value for panelizing or is something else happening?