Scale cake batter between round pan sizes by comparing their surface area.
Usage Tip
For square pans, use side length squared instead of the circle area formula.
How cake pan conversion works
To swap one pan for another, compare their surface area. Divide the new pan’s area by the original pan’s area and you get the factor to multiply your recipe by. Same area means roughly the same batter and bake; a bigger area needs more batter, a smaller one needs less.
scale = new pan area ÷ original pan area
round area = π × (diameter ÷ 2)² · square / rectangle = length × width
Pan area vs volume
Area-based scaling assumes both pans are filled to a similar depth, which is true for most cakes. If the pans are noticeably different depths, scale by volume instead (area × depth) so the batter rises to the same level. The calculator above lets you add a depth for each pan to switch to a volume comparison.
Common pan sizes by area
| Pan size | Shape | Area |
|---|---|---|
| 8″ round | Round | 50 sq in |
| 9″ round | Round | 64 sq in |
| 10″ round | Round | 79 sq in |
| 8×8 | Square | 64 sq in |
| 9×9 | Square | 81 sq in |
| 9×13 | Rectangle | 117 sq in |
| 11×7 | Rectangle | 77 sq in |
| 9×5 loaf | Loaf | 45 sq in |
| 12×17 sheet | Sheet | 204 sq in |
Round to square conversion
| Round pan | Closest square | Note |
|---|---|---|
| 8″ round (50) | 7×7 (49) | Almost identical |
| 9″ round (64) | 8×8 (64) | Practically the same |
| 10″ round (79) | 9×9 (81) | Very close |
Square to rectangular conversion
| Square pan | Closest rectangle | Note |
|---|---|---|
| 8×8 (64) | 11×7 (77) | Rectangle is a bit larger |
| 9×9 (81) | 9×13 (117) | 9×13 is much larger – scale up batter |
| Two 8×8 (128) | 9×13 (117) | Close – a common swap |
8-inch to 9-inch cake pan
Going from an 8″ round (50 sq in) to a 9″ round (64 sq in) increases the area by about 27%, so multiply the recipe by roughly 1.27. Going the other way, from 9″ to 8″, scale to about 0.79 (79%).
9-inch round to 9×13 pan
A 9″ round is about 64 sq in and a 9×13 is about 117 sq in, so a 9×13 holds nearly 1.8× as much. To fill a 9×13 from a 9″ round recipe, multiply by about 1.8; in reverse, scale to about 0.55.
Common pan swaps
- 9″ round ≈ 8×8 square – both about 64 sq in, an easy direct swap.
- 8″ round ≠ 8×8 – the square (64) is larger than the round (50); expect a thinner cake or scale the batter up about 1.27×.
- Two 9″ rounds ≈ one 9×13 – 2×64 = 128 vs 117, close enough for most layer cakes.
How much batter does a pan hold?
As a rough guide for a standard 2-inch-deep pan: an 8″ round holds about 4 cups of batter, a 9″ round about 5–6 cups, an 8×8 about 6 cups, and a 9×13 about 12–14 cups. Fill pans no more than about two-thirds full to leave room to rise.
Brownie and bar pans
Brownies and bars are denser and shallower, so area scaling works well but watch the bake time – a thinner layer in a larger pan cooks faster, a thicker layer in a smaller pan slower. Adjust by a few minutes and test for doneness.
Cheesecake pans
Cheesecakes are dense and often baked in springform pans with a water bath. Convert by area as usual, but expect bake times to shift noticeably with depth, and keep the same water-bath setup for even cooking.
Baking time adjustment tips
- Shallower batter in a larger pan bakes faster – start checking 5–10 minutes early.
- Deeper batter in a smaller pan bakes slower – add time and tent with foil if the top browns first.
- Keep the oven temperature the same; adjust time, not heat.
- Always test with a skewer rather than trusting the clock.