Swapping an 8-inch square for a 9-inch round? They're famously close in area — here's the exact factor.
An 8-inch square is 64 in²; a 9-inch round is about 64 in² too — nearly identical. You can use them interchangeably with no real change to ingredients or bake time.
Geometry is exact area math; temperature and time are directional guidance from baking practice, not formulas. Always test for doneness.
The ingredient scale factor is exact area math. Bake time follows batter depth, not volume — so we give the direction to adjust and a doneness cue rather than a fabricated time. Switch to “keep same batter” if you're not scaling the recipe, just using a different pan.
Converting different pans? Use the full pan size converter.