9x13 to 9x9 Pan Conversion
To bake a 9×13-inch recipe in a 9×9-inch pan at the same depth, multiply every ingredient by 9/13, about 0.69. Making two-thirds of the recipe is the easy version: the layer comes out about 4% thinner, and 3 eggs become 2.
- 5 min read
- Updated 2026-11-03
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| Move | Multiply ingredients by | Layer depth vs. original pan |
|---|---|---|
| 9×13 recipe → 9×9, full batch | 1 (no change) | 144% |
| 9×13 → 9×9, exact area | 9/13 (0.692) | 100% |
| 9×13 → 9×9, two-thirds | 2/3 (0.667) | 96% |
| 9×13 → 9×9, half batch | 1/2 (0.5) | 72% |
| 9×9 recipe → 9×13, unchanged | 1 (no change) | 69% |
| 9×9 → 9×13, exact area | 13/9 (1.444) | 100% |
| 9×9 → 9×13, one and a half | 3/2 (1.5) | 104% |
Depth is calculated from inside pan area and assumes straight sides and similar wall height. Measure across the inside of each pan’s top edge.
Scale your ingredients
Paste your 9×13 recipe into the scaler below, one ingredient per line. It starts at 9/13 for a 9×9 layer at the original depth. Enter 2/3 (0.667) for the easy version, or 13/9 (1.444) to take a 9×9 recipe up to a 9×13; decimals are easier to type on a phone. It scales amounts only, not baking time.
Why the answer is 9/13
A 9×13 pan has 117 square inches of floor; a 9×9 has 81. Divide the new area by the old: 81 ÷ 117 = 0.692. Because the pans share a 9-inch side, the fraction simplifies to 9/13. Enter 9/13 (or 0.692) in the scaler above and every ingredient drops to the amount that keeps the batter at its original depth.
Two-thirds is the practical shortcut
Two-thirds of a 9×13 batch is 78 square inches’ worth of batter spread over 81, so the layer is about 96% as deep. Most cake, bar and brownie recipes absorb that small difference. The arithmetic is friendlier too: 3 eggs become 2, 1½ cups become 1 cup, and ¾ cup becomes ½ cup. The two-thirds recipe guide has a full measure chart. A half batch is simpler still, but its layer is about 28% thinner, so it bakes faster and the edges can dry out.
Why the full recipe is a gamble
Pouring a whole 9×13 batch into a 9×9 raises the batter by 44%. Batter that half-filled a 2-inch-deep 9×13 would stand about 1.44 inches deep in a 2-inch 9×9, roughly 72% full before it rises. Cakes may overflow or sink, and the center lags far behind the edges. Dense brownies that barely rise can sometimes take the extra depth, but they need a much longer bake and a careful check in the middle. If you want to use all the batter, bake the extra in a second small pan or as cupcakes.
Baking time and temperature
Keep the recipe’s oven temperature. At the same depth, a 9×9 often bakes in close to the original time, because the middle of either pan sits 4½ inches from the nearest wall, so heat has about the same distance to travel. Start checking a few minutes before the recipe’s earliest time and go by its own cues: edges pulling away from the pan, a center that springs back, or moist crumbs on a tester for brownies. A thinner half batch can finish noticeably sooner. Glass and dark metal pans brown faster than light metal, so follow the recipe or pan maker’s advice for them.
Going the other way: 9×9 up to 9×13
Multiply by 13/9, about 1.44, for the same depth; enter 13/9 or 1.444 in the scaler above. One and a half times the recipe is the easy version and gives a layer about 4% deeper. The one-and-a-half times guide handles the awkward measures. An unchanged 9×9 recipe in a 9×13 makes a layer only 69% as deep, which suits thin bars but not a cake you want to frost and slice tall.
Eggs that don’t divide evenly
Three eggs times 9/13 is 2.08 eggs, so use 2, or beat the eggs, weigh them without shells and multiply that weight by 0.692. Cover and refrigerate any leftover raw egg right away, and don’t leave it at room temperature for more than 2 hours (1 hour above 90°F), following the FDA’s food storage guidance.
Frequently asked questions
Can I use a 9x9 pan instead of a 9x13?
Yes. Multiply the recipe by 9/13 (about 0.69), or make two-thirds of it. The full recipe would sit about 44% deeper.
Is a 9x9 pan half of a 9x13?
No. A 9x9 has about 69% of the area of a 9x13, so a half batch makes a layer about 28% thinner.
How do I convert a 9x9 recipe to a 9x13 pan?
Multiply by 13/9, about 1.44. Using 1.5 times the recipe makes a layer about 4% deeper.
Do I change the baking time?
At the same depth, often only a little. Keep the temperature, check a few minutes early and go by the recipe’s doneness cues.