What’s happening to me? The minute I went to photograph this dessert I thought, “Rats! I should have made the cobbler in a cast iron frying pan. It would have looked so much more rustic.”

Great. It’s not enough that I’m criticized for being a food snob. Now I’m about to push myself into a whole new level of visual elitism.

Be warned. Not only can this thought process harm your wallet, it can lead to culinary disaster. Using the correct pan size is crucial in baking. Believe me, I’ve scraped enough batter off the bottom of my oven to know you can’t cram big cake batter into a small cake pan. My only solution was, “Don’t do it.” But with an 8-inch cake stand and loads of recipes for 9-inch cakes, I needed a proper fix.

Fortunately, I surround myself with smart people.

## Using Math to Calculate Pan Size

**The solution: **According to Anna Olson, you need to maintain the depth of the batter to avoid spillage. To do this you need to know:

- the surface area
- the percentage of batter the smaller pan holds

To double check my math, I turned to my cyber-friend Laura Laing, author of ** Math for Grownups: Relearn the Arithmetic You Forgot from School.** (Adams Media © 2011). Ironically, the math I needed wasn’t found in her kitchen section. Instead, I found the required formula in two places. The first — surface area — was illustrated in the gardening section*. Technically, area =

*pi*multiplied by the radius of the circle squared. But I can’t figure out how to type the squared symbol, so I’m going to settle on

**For easy calculating, I’m rounding**

*A= π x r x r.**pi*to 3.14.

First, I need to know the surface area of **both** pans:

- Surface area for 9-inch round pan = 3.14 x 4.5 x 4.5 = 63.58
- Surface area for 8-inch round pan = 3.14 x 4 x 4 = 50.24

Now I need to now the percentage of the smaller pan. For the ratio formula, I flipped to the section on crafts. Who knew knitting could be so handy? Here’s how much surface area the 8-inch round pan offers versus the 9-inch pan.

- 50.24 / 63.58 x 100 = 79.02%

That’s 80% in my world. In order for the recipe to work, the 8-inch pan should hold only 80% of the batter intended for the 9-inch pan. So, you pour 80% of your batter into the 8- inch pan. (Use a scale to do this.) This ensures the height of the batter is approximately the same as the original recipe intended, and your cake won’t spill over.

And just what do you do with the remaining 20%? Anna says to bake cupcakes. I’d likely just end up eating it by the spoonful.

**But wait. There’s more!**

This is where math ends and the alchemy begins. Anna says you have to reduce the baking time “slightly”. How much is that? It depends on too many factors to calculate accurately. Reduce the baking time by 5 to 10 minutes, check the cake, and estimate additional cooking time from there — if needed.

So, will my 10-inch cast iron frying pan work for the cobbler? Let’s see.

- Area of 9-inch square pan = 9 x 9 = 81
- Area of 10-inch round pan = 3.14 x 5 x 5 = 78.5
- Percentage of batter the 10-inch pan will hold = 78.5 / 81 x 100 = 96.9 %

Close enough for me. Think I’ll go make another batch and test the theory in the real world.

Got a tricky kitchen calculation need solving? Ask away. With my calculator and a book of handy formulas, I’m unstoppable.

* For those who are curious about the book, the kitchen section in *Math for Grownups* help you can calculate how many tomatoes will fit in a jar, convert common measurements, estimate how long it takes to defrost a turkey (and then cook it!) and allow you to fiddle with measuring spoon fractions.

Thanks for this post! Unfortunately I had to learn the hard way about proper pan sizes, especially with that double chocolate cake recipe I found on a blog. The blogger wrote that she used one 9″ round cake pan and 12 cups of a standard muffin tin. (She was saving the 9″ round in the freezer for later.) I estimated that a 13×9″ baking dish would be sufficient. Apparently it wasn’t! Later I found out that the recipe was adapted from a recipe that called for two 10″ rounds. No wonder it caused a hot mess in my oven. Now, I fill the pans no more than 2/3 full. I rather have a little left than having to clean the spill in the oven. I also use a sheet pan/cookie sheet underneath especially (possible) sticky messes, such as cobbler or pies.

Doing the math, two 10-inch round is 157. But a 9 x 13 square is 117, which is 74.5% of the capacity. No wonder it was a mess.

However, I admit, your 2/3 full rule is pretty practical. I’ll keep that in mind.

Great idea to put a cookie sheet under cobbler or pies. Mine didn’t overflow, but pies can be unpredictable.

Thanks for sharing your story and simple solutions! I’ll put my calculator away now…

I’m not much of a baker (except for fruit pies), which is why you couldn’t find your problem in the kitchen section! So glad you found the book useful. Just goes to show that the same math can apply in lots of different places.

And good on you for figuring out what you needed to do!

Laura, I couldn’t find the answer to that question in ANY baking book. And believe me, over the years I have looked and looked.

Thanks for writing such a helpful book!

Ohhh, how I wish I paid more attention in math class. Just found this post which is not quite what I need but still very helpful. In my case, I need to figure out how to increase the ingredients properly to go from a 9×11 pan to 11×15 pan.

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Hmmm. This is a different problem entirely. You’re looking to fill a pan designed to hold 165 surface inches of batter with a recipe designed to provide 99. Scaling a recipe up by increments is always tricky since things like eggs don’t divide well. Your best bet would be to double the recipe (188 square inches of batter) and bake it in the bigger pan for a bit longer at 25°F lower. Since I have no idea what you are baking, this might not be a good suggestion. It will take longer for the item to bake because it will be slightly thicker and it will take longer for the heat to penetrate the centre given the larger pan size. So much depends on the actual recipe.

If you go this route, write down what you did and how it turned out. You think you will remember, but if you’re like me you won’t. It might take you a couple of tweaks, but based on experience, where there’s a culinary will, there is a way! Good luck.

Thanks for taking the time to think about it! I found a site that listed the pan sizes in cups, and a chef friend helped me figure out that I only needed to increase it by one and a half times, no temperature change. I’m attempting to remake Hostess brand Suzy Q’s, including the homemade marshmallow fluff.

Thanks again!

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Well I just noticed its 2, 10 inch round pans I only have 3,9 inch round pans. What Can I do I don’t have a car to go buy pans. This is the recipe and I spent a lot of money on the ingredients.

http://www.marthastewart.com/260375/ultimate-coconut-cake

I’ve looked at the recipe and think the easiest thing to do is divide the batter evenly amongst your three 9-inch round pans. Bake them at the temperature specified, but reduce the cooking time so the cakes don’t dry out. Try testing them 10 minutes early to gauge their progress. Then, to get the required six layers, just cut each round in half. Actually, this is MUCH simpler than cutting a cake into three layers.

Good luck with this. I’d love to hear how your cake turns out!

i need a 9/9 pan can i use a 8/8 pan

Yes, but you’ll have too much batter. It could overflow. The math works regardless of pan shape. You need 81 square inches but will have only 64. 64 is 79% of 81, which is 80% in my books. That means you have to set 20% of the batter aside in order for it not to overflow. You can always make cupcakes with this leftover batter.

Good luck.

How about if the problem works the other way? I have a recipe which calls for a 7″ round pan for a cherry madeira cake, and the ONLY cake tin I have is a loose bottomed 8″ one. I have never made a cake before, so this could be a disaster!

What would your advice be please and how should I adjust the cooking time if you think I could still give this a go? The recipe calls for it to be baked at 160C for 11/4 – 11/2 hours.

Hmm. I assume by “loose bottomed” you mean your pan has a removable bottom? If so, this kind of pan is designed so you can bake and then easily remove pies and quiches. It works because the pastry forms a barrier. However, it won’t work for cake batter. It would just spill out all over your oven floor.

You’re better off trying to make cupcakes. Use a standard muffin tin (the type with 12 wells) and line the tins with paper muffin cups or grease and flour the wells so the cupcakes come out easily. Fill them 2/3 full. Leave the temperature at 160°C and bake the cupcakes for 20 minutes. Check them. Bake another 10 to 15 minutes based on how cooked they are.

It’s not a perfect solution but it’s better than losing all your batter. (If by chance your pan is as standard 8-inch pan, try baking the cake in it and reduce the time by half an hour, checking at the 50 minute point.).

I hope this helps!

thanks so much for this. idiot proof guide for an idiot making a 5 tier wedding cake (for friends) for the first time!!

You are braver than I am! Homemade cakes are always special. Your friend is lucky to have you.

I’m sure it will be beautiful. I know it will be made with love.

I have a recipe but i dont want to make so much cake as its only for 2 people, the recipe calls for 9 by 13 square and i have 7 by 9 inch square pan. Im so confused should i just make the recipe fully and then just not fill it too high or do u think i should completely change the amounts in the recipe which im scared of doing without further guidance…help!! Heres the recipe http://thepioneerwoman.com/cooking/2009/09/tres-leches-cake/ … Thanks

I’ve taken a look at the recipe. The 7X9 pan is just about half the size of the 9X13, so you

canhalve the recipe using the smaller pan. HOWEVER, the cake calls for 5 eggs and 1/3 cup milk, which are hard to halve. That said, because the cake is drizzled and then iced, I think you can get away with a less than perfect base. I say go for it. I’d love to hear how it works out!How about a conversion from two nine-inch rounds to three six-inch rounds (1.25 inches deep)? I’m making a little smash cake for my daughter. Thanks!

The three 6-inch rounds will hold about 2/3 of the batter that the two 9-inch rounds will hold. You’ll have to make cupcakes with 1/3 of the batter and divide the remaining between the three small pans. Of course, you’ll have to reduce the cooking time. This isn’t a perfect method, but it will at least be a good start. Plus you’ll have cupcakes!

Good luck. I hope your daughter loves her cake.

Thanks – it turned out great!

Super! I’m so glad to hear that. Thanks so much for taking the time to let me know how it worked out. I really appreciate it.

Hope your daughter enjoyed her cake!

Thanks for this – you just saved me a lot of time figuring it out on my own and math is not my forte!

Math isn’t my strong point either Glad you found this post helpful. I don’t worry about pan size nearly as much now that I know this trick.

Happy baking!

Hi guys, I found an app for iPhone on the Apple store that do this, it is called CakeShape and it is a converter from one cake tin to another.

Here is the link: https://itunes.apple.com/us/app/cakeshape/id662754655

I already tried it with 2 cakes and it works pretty good.

Wow! I just checked it out briefly and it looks very helpful. You do need to plug in your ingredients, but if it saves a cake or two, then it’s definitely worth the time and $0.99 price tag. Thanks so much for sharing this with us!

Hello Charmian, I am the dev of CakeShape

I am really glad that you found my app useful. I have planned other updates with more features, so stay tuned…

And if you have some ideas to improve it, do not hesitate to contact me.

I haven’t had a lot of time to play with it. If I have a suggestion, I’ll let you know. Good luck with the updates!

You need to make the app available for droids as well. TKU.

I’m not sure all the platforms the Cakeshape app runs on. I’ll pass your suggestion along. Thanks for taking the time to comment.

I know Denise. In the next 2 months

Thank you the advice

My recipe for carrot cake calls for using two nine inch round pans and baking for 50 minutes. I would like to bake the recipe in a 9X13X2 inch pan. How long would I bake it for in the 9X13X2 inch pan?

This is a bit tricky since carrot cake tends to be heavy. Doing the math, the two rounds require about 127 square inches of surface space combined. The 9×13 provides only 117, and so will be about 10% thicker. Since I don’t know how deep the rounds are meant to be, I’m only guessing here. I’m not sure it will cook without overflowing and I’m not sure the centre will set properly since carrot cake tends to be very moist and heavy. If you have a bundt pan, that might be a safer way to bake it since it will cook from the centre out as well as the outside in.

That said, if you want to try the 9X13, I’d bake it for at least 15 minutes longer, but think it could take more like 20. Switchin pan size isn’t an exact science, so I’d check the cake at 60 minutes and see how set it is. Good luck. I love carrot cake and would hate to see it go to waste!

Thank you, Christie, for your reply. The 9″ round cake pans I have used are 1 1/2 inches deep. The 9X13 is two inches deep so hopefully it won’t overflow when I give it a shot!

I have a delicious and easy recipe for carrot cake if you would like me to email it to you.

Glad to help, Janet. I’d love to hear how your cake turns out. I’m always curious about recipes and would love to see what you’re making. You can email me via my contact form. Happy baking!

Hi Charmian,

I found a recipe that calls for a 9 inch round pans that are 2 inches high. I would like to experiment using 2 mini spring form pans instead and was wondering what the calculations would be. Could you please do the math for me, below are the ingredients listed.

8 ounces chocolate

12 tablespoons unsalted butter

2 teaspoons vanilla extract

1 ¾ cups sliced almonds

¼ cup Flour Mix

½ teaspoon salt

5 large eggs

¾ cup sugar

½ cup fresh raspberries, plus 16 berries for garnish

¼ cup seedless raspberry jam

Chocolate Ganache

5 ounces chocolate

½ cup plus 1 tablespoon heavy cream

Thank you,

Jen

Thanks for sending the ingredients, unfortunately, my calculations are based soley on pan size. I can’t help since I don’t know the size and shape of the mini-pans. There is an iPhone app, CakeShape, that takes ingredients into account as well as pan size. It might be useful if you feel the texture of the cake will be an issue. My method assumes a standard cake.

I know it’s tempting, sometimes essential, to swap pan sizes, but it’s always a risk — especially if you’ve never made the recipe before.

Hi, hoping to get some insight. My recipe calls for a 9 x 13 baking pan but I only have a 8 x 11.. Do I have to make any conversions or will this still be okay to use?

By my calculations, your 8×11 pan will hold only 75% of the intended batter. If you put the entire recipe in it will likely spill over. I wouldn’t recommend doing this. Your best bet, is to put 3/4 of the batter into the 8 x 11 and then make cupcakes with the remaining batter.

All the best with your baking!

Hi there!

I have a recipe for Apple Cheesecake that I got from a restaurant. It’s a commercial size recipe and calls for a 12″ springform pan. I want to make a smaller cake, perhaps halve the recipe. What size pan would I use–6″?

Thanks!

If you halve the recipe, the best bet would be to use a 9-inch round springform pan since it holds just slightly more than 50% of a 12-inch pan. I know a 6-inch

soundslike half, but because of how you calculate the area of a circle (pi X radius squared) it’s not as simple as halving the pan width. Here’s the math. It’s a bit surprising.a 12-inch round pan = 3.14 X 6 X 6 = 113

a 9-inch round pan = 3.14 X 4.5 X 4.5 = 63.58 (this is about 56% of the 12-inch pan)

a 6-inch round pan = 3.14 X 3 X 3 = 28.26 (this is about 25% of a 12-inch pan and would be far too small)

Good luck with your Apple Cheesecake. I hope your half recipe turns out nicely! I’d love to hear if this worked for you.

Hi Charmain,

I need to increase a cake size from a 9 inch 2 layer round cake to a 10 inch 2 layer round cake. I want the 10 inch layers nice and tall. Should I double the recipe? Previously using 1.5 times the batter resulted in pretty flat 10 inch layers.

Thank you!

Sandra

It’s always tricky since some cakes can double nicely and others don’t. Since you’ve already done 1.5 recipes and found it wanting you could probably double the original recipe to produce a high 10-inch version. I say this assuming the cake turned out nicely when you made 1.5 recipes. If, on the other hand, it was heavy and failed to rise or cook properly in the centre, an alternative might be to double the recipe and make 3 10-inch cakes. I’m not sure if that will produce the results you’re looking.

All the best with this cake adventure. I’d love to know what you did and how it turned out.

i have recipe for squars from companys coming and most of them are for 9 by 9 inch pan i want to use 9 by 13 pan what to do???

A lot depends on the recipe itself. If the square is a single layer and reasonably thick, then you could use the 9 X 13 pan and reduce the cooking time. Your batter will be spread more thinly, but most squares are moist enough to cope.

If the square is thin and/or has multiple layers, the 9 x 13 pan is likely too big and your squares will dry out or burn. If this is the case, you could use an 8 x 8 and increase cooking time or you could try this old trick. Place a brick along one short side of the 9 x 13 pan to create a roughly 9 x 9 pan. Pad any gaps between the pan edge and brick with crumpled aluminum foil. Line the pan with aluminum foil, molding it

overthe brick. Spray with cooking spray. Pour the batter into the pan. The brick will act as a dam. Bake your squares until done (it might take longer since the brick can effect the temperature).Good luck!

Hello! I’m making a chocolate cola cake for my brother-in-law’s birthday tomorrow. All the recipes I can find call for a 10″ spring form tin. I only have an 8″ silicone. This silicone is deeper than a tin would be so I had thought if keeping the recipe the same and just cooking it for a bit longer. What would your advise be? Many hopeful thanks in advance

I wouldn’t advise it. Numbers are deceiving. While an 8-inch round cake pan sounds only slightly smaller than a 10-inch, the larger pan will hold almost 64% more batter. Unless the 8-inch pan is really, really deep, the cake is likely to spill over. Plus, being so deep, the batter might not cook all the way through very well.

I’d put 2/3 of the batter into the 8-inch pan and make cupcakes with the remaining batter.

I hope this helps and that your brother enjoys his birthday cake no matter what size pan it comes in.

Thank you for replying – I’ll go and try that!

Hi, im baking this sponge cake and it asks for a 7.1 inch round cake pan, the problem is I only have a 11inch spring form pan and I need the cake for tomorrow, any idea what to do?

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I think I’m too late. The easy answer is make cupcakes.

Not the solution? The small pan has a surface area of about 40 inches. The 11-inch pan has a surface area of almost 95. You might get away with doubling the recipe (2 1/2 recipes would be better but that can be tricky). Keep in mind you would have to adjust the baking time. Some recipes double nicely. Others don’t. It’s risky if you’re not familiar with the recipe.

Yeah. Definitely go the cupcake route if you can.

I have a cheesecake question. I have a recipe for a light cheesecake, 10 inch springform. 200 degrees F, for 3 hours. I want to make mini cheesecakes in 4.5 inch springform pans. 10 inch springform is about 12 cups volume, and 4.5 inch springform is about 2 cups volume. I plan to cut the recipe in half, so only 3 mini springforms. How long should I bake them?

That’s a tricky one. Kudos for doing the math! The alchemy of timing is never an exact science.

Mini-cheesecakes are usually made in muffin tins, and the heat is set at about 300°F. Normally, they bake for less than half an hour. I know the pan you’re using is larger than a muffin tin, but it’s substantially smaller than a 10-inch pan. I’d up the heat to 300°F and check them at about 20 to 25 minutes. They are cooked when the edges are set but the centres jiggle if you shake the pan.

Good luck! I’d love to know what the final timing is.

I am making dressing for thanksgiving and my recipe calls for a 10 inch cast iron skillet.. Which i don’t have. Will a 9×13 glass casserole pan work??

Calls for the skillet for the cornbread…that’s what I am needing the math for… Sorry

Cast-iron and glass have very different rates of heat transfer. I think you will have an issue not only with the pan size, but also with the material used.

The 9 x 13 glass pan will hold about 1 1/2 times the amount the 10 inch cast-iron skillet will. If you were making a single recipe the cornbread will be quite thin.

That said, cornbread is likely very forgiving and as long as you keep an eye on the baked goods the larger glass pan is probably okay. I would check the cornbread at about the halfway mark to gauge how much longer it will need to cook. You will need to use texture instead of timing.

I hope this helps and that your cornbread turns out as you intend.

One more thing. To compensate for the glass baking dish, you might want to lower the oven temperature by 25C.

I found a great sheet cake recipe that calls for a 13 x 18 x 1 inch sheet pan but it looks like a pretty thin layer. As my cake pan is 13 x 18 x 2 inches high, I’d like to double the recipe so the layer is a bit taller.

Can you tell me if this would work – assume I’d need to bake a bit longer? Any advice welcome, it’s for my daughter’s 7th birthday on Saturday! Thanks. Susanne

Hey thanks a ton for the insight!!! Charmian and Laura you made me a mathematician!!

I have an issue here: (may fit snugly into the chain of comments,sorry)

1) When a recipe asks for 2 same size cake pans for a layer/sandwich cake, am in a fix as my oven is small to fit to pans simultaneously. Is there a way out? I do not want to cut the cake into half. I am eager to bake a Victoria sponge cake. Something like this: http://www.bbcgoodfood.com/recipes/1997/classic-victoria-sandwich

PLease help!!

This IS a challenge. I had a tiny oven for years. You can bake them one at a time but this might cause issues with the batter. The first cake will be fine, but the second might suffer from sitting for a half hour. An option might be to bake them at the same time but on different racks, switching half way through the baking. Good luck with this!

Thank you for all the hep!

Glad to assist. I figure if I struggled with this others did too.

Keep baking!

Hi charmain, i have a recipe that asks for a 25cm tube pan but i only have a 28 cm tube pan

can i use it ? And if i reduced the time of baking will it work?

Using a slightly larger tube pan won’t be an issue. Going to a smaller pan often means the cake spills over. The larger pan will hold the batter easily.

You’re right in thinking you will need to reduce the baking time since the cake won’t be as deep. I’d check the cake 15 to 20 minutes before the suggested time and gauge from there.

Good luck! Let me know how your cake turns out!

Thanks charmian you are the best