You can swap a 9-inch round pan for a 10x15-inch jelly roll pan: a 9-inch round pan holds about 8.8 cups and a 10x15-inch jelly roll pan holds about 10.4 cups, so the new pan is about 1.2 times the volume of the old one. That is the whole conversion in one sentence, and everything else on this page follows from it — how deep your batter will sit, how long the bake will take, and whether you should scale the recipe or simply pour the same batter into a different pan. All volumes here are approximate, worked out from the stated capacities with the formula the pan size converter on this site uses, assuming a standard 2-inch depth. If your pans are deeper or shallower than that, measure them with water and use your own numbers instead.

For layer cakes and sponge cakes this swap is all about batter depth: the same batter spread thinner bakes faster and dries out sooner, while the same batter piled deeper takes longer and can stay raw in the middle. The difference between the two pans is about 1.6 cups, which is about 20% more volume. Good swap — the volumes are close enough. A good rule of thumb is that a ratio between 0.75x and 1.35x is a comfortable direct swap, a ratio below 0.75x means the new pan is too small and the batter will overflow, and a ratio above 1.35x means the new pan is much larger and the bake will come out thin and may dry out. At about 1.2x, this swap sits in the comfortable range, so read the fill-level and timing sections before you pour.

The volumes, side by side

Pan Approximate volume Volume in cubic inches Base area (at 2-inch depth)
9-inch round pan about 8.8 cups about 127 cu in about 64 sq in
10x15-inch jelly roll pan about 10.4 cups about 150 cu in about 75 sq in
Difference about 1.6 cups more about 23 cu in —

The cubic-inch figures come from the conversion 1 US cup equals 14.44 cubic inches, so 8.8 cups times 14.44 is about 127 cubic inches and 10.4 cups times 14.44 is about 150 cubic inches. The base areas follow from dividing those volumes by the assumed 2-inch depth. You do not need to memorise any of this — the point is that the ratio, not the diameter or the name on the box, is what decides the swap. Two pans that look almost the same size can differ by a third in volume, and two pans that look very different can be surprisingly close.

How the volumes were worked out

There is no pan-size data file behind this page, so the headline figures come from the stated capacities for these two pans — about 8.8 cups for the 9-inch round pan and about 10.4 cups for the 10x15-inch jelly roll pan — and every other number here is arithmetic from those two figures. For a round pan the volume is pi times the radius squared times the depth; for a square or rectangular pan it is length times width times depth. One US cup is 14.44 cubic inches. All the volumes on this page assume a standard 2-inch depth, which is the depth of most cake pans, loaf pans and pie dishes sold today, and the same assumption the pan size converter uses.

That assumption matters most for special shapes. A bundt pan, a tube pan, a pie dish, a muffin tin or a ramekin does not follow the round-pan formula neatly, because of the centre tube, the sloped sides or the individual cups, so for those pans the stated capacity is the figure to trust, not a calculation from the diameter. What the formula does give you, for any shape, is the way volumes scale: double the depth and you double the volume, and the baking time scales roughly with the square root of the volume ratio. That square-root rule is why a pan that is 1.2 times the volume does not need 1.2 times the baking time — it needs about 1.1 times the baking time, as the table below shows. If you want to check a different pair of pans, or your own pans with their own depths, use the pan size converter and the baking time adjuster rather than guessing.

Fill level: how deep will your batter sit?

Batter depth is the number that decides whether a swap works, and it is easy to work out: depth equals twice the batter volume in cups divided by the pan's capacity in cups, because the pan is assumed to be 2 inches deep. The table shows what happens to the same batter in each pan.

Batter Depth in the 9-inch round pan Depth in the 10x15-inch jelly roll pan
2.9 cups of batter about 0.7 inches deep about 0.6 inches deep
4.4 cups of batter about 1 inches deep about 0.8 inches deep
5.9 cups of batter about 1.3 inches deep about 1.1 inches deep

A cake pan should be filled no more than about two-thirds full. Two-thirds of the 9-inch round pan is about 5.9 cups and two-thirds of the 10x15-inch jelly roll pan is about 6.9 cups, so those are the practical maximum batters for a cake that needs room to rise. If your recipe makes more batter than the safe fill of the new pan, do not pour it all in: bake the extra batter in a second pan, in ramekins, or as cupcakes, and keep the main pan at or below two-thirds. Overfilling is the single most common pan-swap mistake, and it shows up as batter spilling over the rim in the oven, a cake that sinks in the middle, and a raw centre under a burnt top.

If the new pan is more than about 25% smaller than the old one — a ratio below 0.75x — the overflow risk is serious and you should split the batter or choose a larger pan. If the new pan is much larger — a ratio above 1.35x — the opposite problem appears: the batter spreads into a thin layer, bakes fast, and can dry out before it has properly set. At about 1.2x this swap avoids both extremes, but the two-thirds rule still applies, and it is worth measuring your batter in cups before you pour so you know where you stand rather than finding out in the oven.

Baking-time adjustment

Baking time scales roughly with the square root of the volume ratio, so with a ratio of about 1.2x the time factor is about 1.1x. Multiply the recipe's time by that factor to get a starting point, then check early.

Original time in the 9-inch round pan Adjusted time in the 10x15-inch jelly roll pan
25 minutes about 27 minutes
30 minutes about 33 minutes
35 minutes about 38 minutes
40 minutes about 44 minutes
45 minutes about 49 minutes
50 minutes about 55 minutes
60 minutes about 66 minutes

A 35-minute bake becomes about 38 minutes and a 45-minute bake becomes about 49 minutes. Those are approximate starting points, not promises: ovens vary, dark pans bake faster than light ones, and a batter with fruit or a wet filling takes longer than a plain sponge. Start checking five to ten minutes before the adjusted time. A cake is done when a skewer inserted in the centre comes out clean or with a few moist crumbs, the top springs back when pressed lightly, and the edges have just started to pull away from the sides of the pan. For custards and cheesecakes, look for a gentle wobble in the centre rather than a firm set — they finish setting as they cool. The baking time adjuster will do this calculation for any time and any pair of pans.

Worked examples

Example 1: a chocolate fudge cake

A recipe for chocolate fudge cake is written for the 9-inch round pan and makes about 2.9 cups of batter, baked for 35 minutes. Poured into the 9-inch round pan that batter sits about 0.7 inches deep; in the 10x15-inch jelly roll pan it sits about 0.6 inches deep. The adjusted baking time is about 38 minutes. Grease and line the new pan the same way you would the old one, pour the batter in, and put it on the middle shelf of a preheated oven. Check it at about 31 minutes with a skewer: if the skewer comes out wet, give it another five minutes and check again. The rich, moist crumb is the thing to protect here, so do not open the oven door in the first two-thirds of the bake, when the cake is still rising and a draught can make it sink.

Example 2: a lemon drizzle cake

Now take lemon drizzle cake, written for the 9-inch round pan, making about 5.9 cups of batter. In the 9-inch round pan that batter is about 1.3 inches deep; in the 10x15-inch jelly roll pan it is about 1.1 inches deep. If the recipe bakes for 45 minutes in the old pan, allow about 49 minutes in the new one and start checking at about 41 minutes. Because the layer is thinner here, the edges will colour first, so watch the rim and be ready to cover the top loosely with foil if it browns too fast. If you want the bake to come out exactly as the recipe intended, scale the recipe instead: multiply every ingredient by about 1.2x, which turns 5.9 cups of batter into about 7.1 cups, and use the recipe scaler to do the arithmetic for the whole ingredient list.

Example 3: scaling the recipe to fit the new pan

Suppose the recipe makes about 4.4 cups of batter and you want the same batter depth in the 10x15-inch jelly roll pan that the recipe had in the 9-inch round pan. Multiply the batter by the volume ratio, about 1.2x, which gives about 5.3 cups of batter. In practice that means multiplying every ingredient by 1.2 — flour, sugar, butter, eggs and leavening alike — and keeping the oven temperature the same. A 4.4-cup batter at about 1 inches deep in the 9-inch round pan becomes a 5.3-cup batter at about the same depth in the 10x15-inch jelly roll pan, and the baking time is then close to the original time, with the square-root adjustment from the table as a starting point. This is the best option when the ratio is large or when the bake is fussy, such as a cheesecake or a genoise, where depth changes the result more than a plain sponge. For a simple traybake or a loaf, the direct swap with an adjusted time is usually good enough, and scaling is optional.

What can go wrong, and how to fix it

The failure modes of a pan swap are predictable, and each one has a fix. Overflow happens when the new pan is too small or overfilled: the batter rises over the rim, burns on the oven floor, and the cake sinks because it lost its structure. The fix is to fill no more than two-thirds full and to put a baking tray underneath as insurance, not as a plan. A dry, thin bake happens when the new pan is much larger: the batter spreads thin, the surface dries before the crumb sets, and the edges overbake. The fix is a shorter time, an earlier check, and, if the layer is very thin, a temperature drop of about 10 degrees Fahrenheit for the second half of the bake. A raw centre happens when the new pan is much smaller or deeper: the outside sets and browns while the inside is still liquid. The fix is a longer, gentler bake — sometimes with foil over the top — and a skewer test in the very centre, not near the edge.

Pan material matters too. A dark metal pan absorbs more heat and bakes faster than a light-coloured one, a glass dish bakes more slowly but holds its heat longer, and a silicone mould needs a baking tray underneath for support and often a few extra minutes. If you are swapping both the size and the material at once, change only the time at first and check early, because two changes at once make it hard to know which one caused a problem. And always preheat properly: putting a cake into an oven that is still heating up adds an unknown amount of time and an uneven rise, whatever pan you use.

Practical guidance

Grease and line the new pan the way the recipe asks for the old one, but remember that the shape changes what lining means: a round pan needs a circle of baking paper on the base, a loaf pan needs a sling of paper that overhangs the long sides so you can lift the loaf out, and a bundt or tube pan needs every crease greased, because a stuck bundt is a ruined bundt. Let the bake cool in the pan for about ten minutes before turning it out, unless the recipe says otherwise — a hot cake is fragile, and a cake left in the pan too long goes soggy from trapped steam. Cool on a wire rack so air can circulate underneath.

Keep notes the first time you make a swap: write the pan you used, the batter volume, the adjusted time and the actual time on the recipe card. The next time you make the same recipe, you will have your own number instead of an approximation, and your own number is always better than a table. If you bake the same recipe often in the new pan, that note is worth more than any converter. And if you are buying a new pan to match a recipe, buy by volume, not by diameter: a 9-inch round and an 8-inch square hold almost the same amount, while two 9-inch rounds from different makers can differ by a cup because one is deeper than the other.

Frequently asked questions

Will the cake be thinner or thicker in the new pan?

It depends on the direction of the swap. Going from the 9-inch round pan (about 8.8 cups) to the 10x15-inch jelly roll pan (about 10.4 cups) makes the batter thinner for the same recipe, because the volume ratio is about 1.2x. A thinner layer bakes faster and can dry out, so watch it closely and consider lowering the oven temperature by about 10 degrees Fahrenheit if the layer is much thinner. A thicker layer needs more time at the same temperature, and the centre is the last part to cook, so test it with a skewer before you take the pan out.

Do I need to change the oven temperature when I change pans?

Usually not. Keep the temperature the recipe gives and change the time instead, because temperature changes the crust and the rise in ways that are harder to predict than a time change. The one exception is a much thinner layer in a much larger pan: there, dropping the temperature by about 10 degrees Fahrenheit (about 5 degrees Celsius) for the last part of the bake can stop the edges drying out while the centre finishes. Always use an oven thermometer if you have one, because many home ovens run 10 to 25 degrees off the dial, and that error matters more than any pan swap.

Can I scale the recipe instead of just swapping the pan?

Yes, and for a big ratio it is the better option. To keep the same batter depth in the 10x15-inch jelly roll pan as the recipe had in the 9-inch round pan, multiply every ingredient by about 1.2x. So a recipe using 4 cups of batter becomes about 4.8 cups of batter, and a recipe using 200 grams of flour becomes about 240 grams. Scale the leavening by the same factor, keep the oven temperature the same, and use the adjusted baking time from the table. Our recipe scaler tool does this arithmetic for a whole recipe at once.

What if my pan is a different depth from the standard 2 inches?

The volumes on this page assume a standard 2-inch depth, which is what most cake pans, loaf pans and pie dishes are. If your pan is deeper or shallower, its real volume is different: volume is base area times depth, so a 3-inch-deep pan holds about half as much again as a 2-inch pan of the same footprint. Measure your pan with water if you are unsure — pour in measured cups until it reaches the brim, and use that number instead of the figure here. Never fill a pan above two-thirds, whatever its depth.

How do I measure my pan's real volume at home?

Put the empty pan on a scale or on the counter, then pour in water one measured cup at a time until it reaches the brim, counting as you go. That count is the pan's brim volume in cups. The usable volume is about two-thirds of that, because batter needs headroom to rise. Compare your measured number with the approximate figures on this page — about 8.8 cups for the 9-inch round pan and about 10.4 cups for the 10x15-inch jelly roll pan — and if they differ by more than about a cup, trust your measurement, because pan makers round their sizes and depths vary.

Related links