Cake Pan Size Converter
Swap cake pans: find how much to scale the recipe to fill a different round, square or rectangular pan, or estimate the new bake time when the same batter goes into a different pan.
Last updated: October 2026
Result
44.3 minutes
Formula below · 2 sources (kingarthurbaking.com, ice.edu) · Updated Oct 2026
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About this calculator
Pans are compared by area. A round pan's area is π × (diameter ÷ 2)², a square's is side², a rectangle's is length × width. A 9-inch round holds 63.6 sq in, an 8-inch round 50.3, an 8-inch square 64, a 9 × 13 rectangle 117.
Recipe multiplier
To fill a new pan to the same depth as the recipe intended, scale every ingredient by the ratio of the pans' volumes: (new area × new depth) ÷ (original area × original depth). With equal depths this is just the area ratio: a recipe for a 9 × 13 pan (117 sq in) needs a multiplier of 0.54 for one 9-inch round. Eggs rarely divide neatly, so round to the nearest practical amount.
Bake time for the same batter
If you pour the same batter into a different pan, its depth changes with the inverse of the area: the batter in an 8-inch round sits (9 ÷ 8)² = 1.27 times deeper than in a 9-inch round. Bake time depends mostly on how deep the batter is, so the calculator scales the time by the same ratio. This is a rough starting point, not a tested time: start checking 10 minutes early and go by a toothpick or an internal temperature, not the clock. Deep batter (more than about 2 inches) bakes more evenly at 25 °F lower with a little extra time.
Fill pans no more than about two-thirds full so the cake has room to rise.
| Pan | Area (sq in) | Share of a 9 × 13 recipe |
|---|---|---|
| 6-inch round | 28.3 | 0.24 |
| 8-inch round | 50.3 | 0.43 |
| 9-inch round | 63.6 | 0.54 |
| 10-inch round | 78.5 | 0.67 |
| 8-inch square | 64 | 0.55 |
| 9-inch square | 81 | 0.69 |
| 9 × 13 rectangle | 117 | 1.00 |
| 9 × 5 loaf | 45 | 0.38 |
How to use
Choose what to calculate, then describe both pans in inches. The default moves 35 minutes of batter from a 9-inch round to an 8-inch round: 35 × 63.6 ÷ 50.3 = 44.3 minutes as a starting estimate; check it from about 35 minutes. To fit a 9 × 13 recipe into two 8-inch rounds, choose Recipe multiplier, set the original pan to Rectangular 13 by 9 and the new pan to Round 8: one round needs 0.43 of the recipe, so two rounds use about 86%, and the full recipe would fill them a little deeper than intended.
Frequently asked questions
Can I bake a 9x13 recipe in two 9-inch round pans?
Yes. A 9 × 13 pan holds 117 sq in and two 9-inch rounds hold 127 sq in, so the batter will be slightly shallower. Keep the oven temperature and start checking about 5 minutes early.
How do I scale a recipe for a bigger pan?
Choose Recipe multiplier and enter both pans. Going from an 8-inch to a 10-inch round multiplies the area by (10 ÷ 8)² = 1.56, so use about 1.5 times every ingredient.
Should I change the oven temperature for a different pan?
Usually not. For a much deeper layer, lowering the oven by about 25 °F and baking longer keeps the edges from overbaking before the center sets. Shallow layers bake faster at the same temperature.
How accurate is the bake-time estimate?
It is a starting point. Heat reaches the center more slowly in deeper batter, but oven, pan material and batter type all matter, so start checking early and use a toothpick or cake tester.
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