How Long Do I Bake A 12 X 18 Sheet Cake?

Baking By SugarMama5 Updated 20 Jul 2015 , 3:56pm by Susan H

SugarMama5 Posted 11 Nov 2010 , 3:59am
post #1 of 29

I am making three 12 X 18 sheet cakes for a fundraiser this weekend. How long should I bake them for? I am planning on using the Duncan Hines cake mixes for them. I also was planning on using 3 mixes per pan (roughly), does that sound about right?

Oh, so much baking to do... I hope it goes smoothly!

Thanks in advance for any help or tips! icon_smile.gif

28 replies
Corrie76 Posted 11 Nov 2010 , 4:25am
post #3 of 29

set the timer for 45 minutes....but plan on that being the starting time of you checking the cakes for doneness, it could take an hour or more. Really, it's hard to say without knowing your oven, how deep the batter is, what kind of pan it's sitting in. Hope it all works out for you, sounds like a lot of work ahead! icon_smile.gif

leah_s Posted 11 Nov 2010 , 4:26am
post #4 of 29

"Until it's done."

Truly, never bake by time. Bake until it's done.

SugarMama5 Posted 11 Nov 2010 , 4:39am
post #5 of 29

a BIG THANKS!!! icon_biggrin.gif Great info!

I forgot o ask one more question... do I NEED a heating core? I don't have one, is there something I can do instead of a heating core?

indydebi Posted 11 Nov 2010 , 9:11am
post #6 of 29

I also use 3 (betty crocker) cake mixes per pan.
I never use flower nails or heating cores.
I always use baking strips.
I always reduce my oven temp.
I never use a timer. Never.
My answer to "how long?" is always "until its done". (My kids HATE it when I tell them that!)

SugarMama5 Posted 11 Nov 2010 , 4:39pm
post #7 of 29
Originally Posted by indydebi

I also use 3 (betty crocker) cake mixes per pan.
I never use flower nails or heating cores.
I always use baking strips.
I always reduce my oven temp.
I never use a timer. Never.
My answer to "how long?" is always "until its done". (My kids HATE it when I tell them that!)

Really? No heating cores at all? Good to know, I'm going to try it without and do as you said.

If I reduce the heat from 350 to 325, is that about right? That's what the Wilton website said for 12x18 sheet cake. How full do you fill your pan? Do you use the entire 3 mixes in one pan?

I never ever realized baking large cakes could be so tricky! icon_wink.gif Thanks for the tips!

LOL about your kids hating the 'when it's done comment'... thanks for the laugh! icon_biggrin.gif

indydebi Posted 11 Nov 2010 , 4:57pm
post #8 of 29

325 ..... all 3 mixes in one pan.

SugarMama5 Posted 11 Nov 2010 , 6:17pm
post #9 of 29

I did it just as you said indydebi... it worked! I took about 54 minutes at 325. One sheet cake down, 2 more to go!

Phew... big sigh of relief!

THANKS AGAIN!! icon_biggrin.gif

Minstrelmiss Posted 11 Nov 2010 , 6:31pm
post #10 of 29

Yeah you icon_biggrin.gif

dashang Posted 30 Aug 2013 , 7:30pm
post #11 of 29

how thick (inches) the cake turned out? Congratulations... I need to make a 2D porsche car cake for my husband and have to use 12x18 sheet cake and from there i will carve the porsche stencil :) *fingers crossed* :)

SugarMama5 Posted 7 Sep 2013 , 10:31pm
post #12 of 29

AIt was about 2" high. I used the 12x18x2" pan. Hope that helps :)

shortie63 Posted 9 Jun 2015 , 1:36am
post #13 of 29

Hi everyone!

I'm about to make my first ever theme cake for a graduation party for this weekend. 

I'll be using a 10x15x3 pan, 2 boxes of cake mix and fingers crossed!

I've Never made a cake this big and I am a little nervous about baking times.  I am making a practice cake tmrw.

Any tips you can throw my way will be appreciated!!

Please send me ideas. Thanks!

Bonne Bouche Posted 9 Jun 2015 , 2:47am
post #14 of 29

12 x 18 x 2 pan 325 for 40 minutes at least.  Start checking at 40 minutes and add until "its done."  I don't use cake mixes so mine might be a little longer to bake.

shortie63 Posted 9 Jun 2015 , 4:34am
post #15 of 29

Thank you for responding Bonne!!!   Im making a test cake tomorrow.   Wish me luck!

shortie63 Posted 9 Jun 2015 , 4:33pm
post #16 of 29


So I just took my test cake (10x15x3) out of the oven and inserted toothpick in different areas to see if it was doneand Wallahhh!!!  Toothpick came out clean every time!   

I used 2 boxes of Pillsbury Classic Yellow, baked for close to an hr, wet 2 long wilton baking cloth strips around the pan and the cake came out leveled on top!

I would post a pic but dont know how here

thanks for the tips Bonne!!!

shortie63 Posted 9 Jun 2015 , 9:59pm
post #17 of 29

Arghhhhhh!  So I made the 10x15x3 cake this morning.  When I inserted the toothpick throughout the cake for doneness it came out clean eveey time!

When I sliced into it just now it looked a bit moist, more than it should be way more.

It baked close to an hour.  My damn timer shut off with a min remaining so I don't know what happened


Im making another test cake now.  I cannot f.... up the 2 layer graduation cake for this wknd

Bonne Bouche Posted 10 Jun 2015 , 12:01am
post #18 of 29

Is the cake rising up past the rim of the pan more than about 1/2"?  If the cake rises too far above the edge of the pan the center will not cook before the edges over bake, even if it's level.  What temp did you use?  Is your oven accurate or close to it?

shortie63 Posted 10 Jun 2015 , 12:15am
post #19 of 29

The pan is 3 inches deep and the cake rose nicely and dis not over flow at all.

I baked at 325 for approx 45-50 mins.  Oven is acc.

I just took out my 2nd test cake and it's cooling now.

Nice and level and bounced back when I touched it with finger and toothpick came out clean in various places

We'll see how this one turns out

do u know how to share a pic?

Bonne Bouche Posted 10 Jun 2015 , 1:32am
post #20 of 29

Not here.  I've had that happen to me with scratch cakes-- turned out to be a recipe problem-- just too much moisture in the recipe (it was a chocolate cake).  I had used the recipe on smaller cakes but when I doubled it for a 12 x 18 pan it came out like a brownie-- had to find a different recipe for larger pans.  I know you use mixes, are adding to the mixes?  Maybe you need to think about any additions (pudding etc) that may be effecting the moisture of the cake.


shortie63 Posted 10 Jun 2015 , 2:07am
post #21 of 29

no I didn't add anything to the mixes but I'm putting that behind me loll

I just cut up the test cake for my husband and it came out perfectly moist and looks great !!  he loves it and I cut up slices for my neighbors and I feel confident that the graduation cake two layers will come out perfect for the weekend I'll keep you posted and if there's a way to post the final product I will

Susan H Posted 19 Jul 2015 , 11:33pm
post #22 of 29

I need to bake a half sheet cake, using  12x18x2 pan.  I have previously used 3 Pillsbury white cake mixes (has pudding in mix) based on above and have had good success.  This time I will use the same cake mix, but with the following ingredients:

1 package small pudding

1/2 cup each of  OJ, oil, milk

4 eggs

I generally make 1 box for a bundt cake...I also reserve 1/4 of batter to mix with 3/4 cup hershey syrup.  This is poured on top of the remainder of cake mix in the pan.

My question if based on above does anyone know if this could not bake well given what is added into the recipe?  Appreciate any help you can is for a special occasion so want to get this right!  and I will be baking it the day of the event!

Bonne Bouche Posted 19 Jul 2015 , 11:59pm
post #23 of 29

Low and slow. I bake at 325 no convection 35-40 min or until done. 

Susan H Posted 20 Jul 2015 , 12:28am
post #24 of 29

thanks!  so you think with what I am adding to the mix I should be fine?

Bonne Bouche Posted 20 Jul 2015 , 12:37am
post #25 of 29

Yea, I think you'll be okay-- slow baking will not hurt it and keep it from rising too much in the center.   The time I gave you is for a pan that is about 1/2 full.  If your batter amount is closer to 2/3 or 3/4 full you are going to have to bake it longer of course.  You might want to consider going down to 310-15 if your pan is that full.  If you have an oven light turn it on and look inside at about 35 minutes-- if it looks like it's getting there check it.  I'm a scratch baker so I don't know how full the pan is with that many cake mixes,  I use one scratch recipe for one layer of a 12 x 18 and I bake them one at a time for a 3 layer cake.  My batter only fills to just under 1/2 full and 35-40 min at 325 works out perfect every time.

Susan H Posted 20 Jul 2015 , 1:18am
post #26 of 29

thanks very much!  Great info!  I plan to leave the cake in the pan with a chocolate glaze and some nuts on top, so not too worried about the center being higher for this cake.  Just want to be sure it is cooked and rises :)  thanks again!  really useful info!

Susan H Posted 20 Jul 2015 , 1:19am
post #27 of 29

one other question...I have never used baking strips...are they necessary?

indydebi Posted 20 Jul 2015 , 2:02pm
post #28 of 29

Necessary?  No.  But ..... a kitchen aid mixer isn't "necessary" to mix icing but it sure turns out better!  The baking strips cool the sides of the pan so the cake doesn't cook faster on the edges than it does in the center ..... prevents doming and prevents wasting cake (after you trim it flat). Your baked cake is higher since the edges and the center rise at the same rate and you don't trip NEAR as much.

Ironically, I baked a cake last night for my daughter's boyfriend's birthday.  I had like 2 hours notice ("Mom, can you make Tony a BD cake for dinner tonight?"  And of course mom says "yes"!) so I just mixed the batter and threw the pans in the oven w/o the strips.  My cakes that are usually 2" tall ended up being between 1" and 1.5" tall.  I was very thankful I planned on making a 4 layer cake!  But instead of being 8" tall, it was only about 6" tall.  Baking strips .... or lack of them ... make the height diff.  For family, it was no big deal, but for a client, I would have been devastated.

Susan H Posted 20 Jul 2015 , 3:56pm
post #29 of 29

ok, you convinced me!  just picked up the baking strips and will give it a try!  I took a cake decorating class just for fun years ok and would love to get back into this...need some good scratch recipes for cake to try my hand at real baking :)  thanks very much for the input!!

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