Cake Pan Converter
Convert cake recipes between round, square, and rectangular pans by pan area.
Returns the batter multiplier, the bake time change, and overflow warnings.
Swapping cake pans comes down to one number: the surface area of the pan. Match the area and the batter sits at the depth the recipe intended, which is what actually controls how the cake bakes. Diameter and shape are just the route to that number.
Working out the area
Round pan = π × radius² Square or rectangular pan = length × width
A 9-inch round is π × 4.5² = 63.6 square inches. An 8×8 square is 64. Those two pans are all but identical, which is why that swap turns up in so many recipe notes.
Standard pans
| Pan | Area | Holds |
|---|---|---|
| 8 × 2 in round | 50 sq in | 6 cups |
| 9 × 2 in round | 64 sq in | 8 cups |
| 10 × 2 in round | 79 sq in | 11 cups |
| 8 × 8 in square | 64 sq in | 8 cups |
| 9 × 9 in square | 81 sq in | 10 cups |
| 9 × 13 in rectangular | 117 sq in | 14 cups |
| 9 × 5 in loaf | 45 sq in | 8 cups |
| 10 in bundt | ring shape | 12 cups |
Capacities are measured to about half an inch below the rim, which is why they come out a little under area × depth.
Scaling the recipe
Multiplier = new pan area ÷ original pan area
A recipe written for a 9-inch round (63.6 sq in) going into an 8-inch round (50.3 sq in): 50.3 ÷ 63.6 = 0.79. Use 79% of every ingredient. Or bake the full recipe in two 8-inch pans and stack them.
About bake time
If you scale the recipe, the batter ends up the depth it was meant to be, so the change is modest. It is not zero, though. A wider cake still takes longer than a narrow one at the same depth, and published pan charts bear that out: an 8-inch round runs 30 to 35 minutes at 350°F where a 12-inch runs 35 to 40 at 325°F. Once a pan is 12 inches or more across, drop the oven 25°F so the edge does not set and brown long before the center does.
If you don’t scale, and just pour the recipe as written into a different pan, that is when time changes. The batter gets deeper or shallower, and roughly every 25% change in depth shifts the bake time by about 10%.
Swaps worth knowing
- 9-inch round and 8×8 square: 64 vs 64 sq in. As close as it gets, and no scaling at all.
- 9×9 square and 10-inch round: 81 vs 79 sq in. Also a straight swap.
- 9×5 loaf and 8-inch round: 45 vs 50 sq in. The round is 11% bigger, so the loaf comes out a little taller. Most batters shrug that off.
- Two 8-inch rounds and one 9×13: 101 vs 117 sq in. The sheet is about 16% bigger, so the layers land a bit thicker than the sheet cake would.
One thing area cannot tell you is whether the new pan is deep enough. A 2-inch pan will not hold what a 3-inch pan held, however well the areas match. Fill any cake pan somewhere between half and two-thirds and you have room for the rise.
Bundt and tube pans sit outside all of this. The hole in the middle changes how heat gets to the center, so go by the stated cup capacity rather than by any area you could measure off the rim.
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