Pan maths
Cake Pan Size Converter
The recipe says 9-inch round and the tin in your cupboard is 9 × 13. Say what the recipe was written for and what you want to bake in, and this works out how much batter the new pan takes, how deep that batter will sit, and what the depth does to the oven temperature and the bake time. Round, square, rectangular, loaf, bundt and muffin pans all measure the same way here, in inches or centimetres. Paste the ingredient list if you want every amount back in grams and cups.
Nothing you type leaves this device — the arithmetic runs in your browser and the page keeps no copy.
The pan swap
Put in both pans and press Convert the pan. You get the batter the new pan takes, the depth that batter reaches, the oven temperature and the time to start checking — all worked out here, with nothing sent anywhere.
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Batter the new pan takes
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How deep the batter sits
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Oven temperature
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Bake time
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Worth a second look
Your amounts, converted
| Ingredient | In the recipe | In your pan | Grams | US cups |
|---|
Every common pan against the recipe's pan
| Pan | Batter it takes | Times this recipe |
|---|
How to convert a cake pan size
- Measure both pans across the top. Diameter for a round tin, width for a square or rectangular one, width and length for a loaf pan. Measure rim to rim, not across the base — a 9-inch tin is usually about 8 1/2 inches across the bottom.
- Add the depth. Depth is the third measurement and the one most people skip. An 8-inch round that is 2 inches deep takes about 4 2/3 cups of batter; the same pan 3 inches deep takes about 7 cups, so the depth changes the answer as much as the width.
- Say what the recipe's oven was set to and how long it bakes. The converter adjusts both, and tells you when to start checking rather than giving one fixed minute.
- Paste the ingredient list if you want the amounts too. Every line comes back with the new amount, the gram weight where one can be worked out and the US cup measure beside it. Lines with no amount, like "salt to taste", are carried through as written.
Reading the pan swap
A pan swap is a volume question. Each pan's capacity here is worked out from its footprint — a circle, a rectangle, a loaf, a ring with the tube taken out, or the cups of a muffin tin — multiplied by the depth it is normally filled to. Round, square, rectangular and muffin pans are filled about two-thirds up; loaf and bundt pans about three-quarters. That is why a 9 × 13 pan takes roughly 10.9 cups of batter while a 9-inch round takes about 5.9: the rectangle has about 1.8 times the footprint, so the recipe doubles.
The temperature and time adjustment follows one rule, stated plainly. If the batter ends up more than about 25% deeper than it was, the oven goes about 25 °F cooler and the bake takes about a quarter longer, because a deep middle needs time to set before the outside dries out. If it ends up more than about 25% shallower, the opposite: about 25 °F hotter and about a quarter quicker. Between those two lines the numbers slide rather than jump, so a 10% change in depth gives a small nudge instead of a cliff edge — and if you scale the recipe to fit the new pan, the batter depth does not change at all, so the oven stays where it was.
If you would rather leave the oven alone entirely, keep the batter the same depth as the recipe's pan. That is exactly what "scaling the recipe into my pan" does, and it is the reason the multiplier changes while the temperature and time stay put.
Batter each common pan takes
These are the pans most kitchens already own, worked out with the same arithmetic the converter uses — footprint times the depth the pan is filled to.
| Pan | Rim depth | Footprint | Batter it takes | To the rim |
|---|---|---|---|---|
| 6 in round | 2 in | 28.3 sq in | 2.6 cups | 3.9 cups |
| 8 in round | 2 in | 50.3 sq in | 4.7 cups | 7 cups |
| 9 in round | 2 in | 63.6 sq in | 5.9 cups | 8.8 cups |
| 8 × 8 square | 2 in | 64 sq in | 5.9 cups | 8.9 cups |
| 9 × 9 square | 2 in | 81 sq in | 7.5 cups | 11.2 cups |
| 9 × 13 rectangle | 2 in | 117 sq in | 10.9 cups | 16.2 cups |
| 8.5 × 4.5 loaf | 2.5 in | 38.3 sq in | 5 cups | 6.6 cups |
| 9 × 5 loaf | 2.5 in | 45 sq in | 5.8 cups | 7.8 cups |
| 10 in bundt, 3.5 in tube | 3.75 in | 68.9 sq in | 13.4 cups | 17.9 cups |
| 12-cup muffin pan | 1.25 in | 71.3 sq in | 4.1 cups | 6.2 cups |
Manufacturers quote the capacity of a pan to the rim, which is about 1.4 times the numbers above. Both are right; they answer different questions. "To the rim" is what fits; the batter column is what a recipe normally asks for.
What a pan swap cannot fix
- It cannot promise the same crumb. A thin layer in a big pan bakes into something more like a bar than a sponge, even when the arithmetic is perfect. Moving between shapes of similar depth is the safe swap; moving from a deep tin to a shallow sheet pan is a different cake.
- It does not read your oven. Ovens run hot or cool by 25 °F without saying so. The temperature here is a starting point from the recipe's own setting, not a measurement of your oven.
- It cannot hear the batter. Chemical leaveners, salt, eggs and flavourings are multiplied with everything else, but an amount that lands on 3.7 eggs gets flagged rather than rounded away — you decide what to do about it.
- It does not fetch a recipe. There is no scraping and no network call anywhere on this page: paste what is in front of you.
- It stays out of sourdough timing. A different pan changes the shape of a loaf, but proofing is its own question — the sourdough baking schedule calculator handles that side of the bake.
Questions about pan sizes
How do I convert an 8-inch round cake to a 9-inch round pan?
By base area, and the arithmetic is quick. An 8-inch round has a footprint of about 50 square inches and a 9-inch round about 64, so the bigger pan takes roughly 1.27 times the batter — call it a quarter again. With the depths equal, the batter ends up at the same depth in both pans, so the oven temperature and the bake time do not need to change. This converter does that sum for you and also tells you what you would need if the pans are not the same depth.
Can I bake a 9 × 13 cake recipe in a bundt pan?
Often, yes — a 9 × 13 pan takes about 11 cups of batter at the level it is normally filled to, and a 10-inch bundt with a 3 1/2-inch tube takes around 13 cups, so the sheet-cake recipe comes up a little short. The shapes also behave differently: a bundt bakes from a central tube as well as the outside, so the middle sets faster than it would in a sheet pan. Pick both pans in the converter and read the batter figures first; if the bundt wants more batter than the recipe makes, scale the recipe up by the multiplier shown.
Do I need to change the oven temperature when I change pans?
Only when the depth of the batter changes — and when you scale the recipe to fit the new pan it usually does not. Keep the batter at the same depth and the temperature stays where the recipe put it. If the batter ends up more than about 25% deeper, drop the oven about 25 °F and give it roughly a quarter longer; more than about 25% shallower and it is the other way round, 25 °F hotter and about a quarter quicker. This tool applies that rule to your own numbers rather than making you guess.
How do I measure a cake pan?
Across the top, rim to rim, not across the base. Most cake tins taper, so the base is roughly half an inch narrower than the rim — a pan sold as 9-inch measures about 8 1/2 inches across the bottom. Then measure the depth from the inside base to the rim, because depth is what decides how much batter the pan holds: an 8-inch round 3 inches deep takes about 7 cups where the 2-inch version takes about 4 2/3.
How many muffins does a cake recipe make?
Divide the batter by what one cup of the tin holds. A 12-cup muffin pan takes about 4 cups of batter in total, so a cup holds roughly a third of a cup, and a recipe that makes about 5 1/2 cups of batter fills the tin and leaves enough for two or three more. Set your target pan to the muffin pan in the converter and it gives you the count directly.
Does a loaf pan hold the same as an 8-inch square pan?
Not quite, and depth decides it. An 8 × 8-inch square pan is about 64 square inches and an 8 1/2 × 4 1/2-inch loaf pan about 38, so the square takes noticeably more batter at the same depth. The loaf is also filled higher — about three-quarters up rather than two-thirds — because the dough is meant to rise above the rim. That is why a quick bread and a brownie recipe of similar weight behave differently in the oven.
Why does the pan's depth matter so much?
Because a pan is a volume, not an outline. Capacity is the footprint multiplied by the depth it is filled to, so two pans with the same width can take very different amounts of batter. It also decides what happens in the oven: the same batter poured into a shallow pan sets quickly and browns, while a deeper pan needs a gentler oven and a longer bake for the middle to cook before the edges dry out.
Bake something in that pan
Once the pan is sorted, the recipe is the easy part. These are the Bakehouse bakes that depend on getting the tin right:
- Banana bread — a loaf pan bake, and the one people most often want to move into a different tin
- Sourdough focaccia — a sheet-pan bake where the depth of the pan decides the crumb
- All the recipes — every cake, loaf and muffin in one place
- Recipe Scaling Calculator — when the batch changes by servings rather than by pan
- Cups to Grams Converter — for one ingredient at a time