Also, Saturdays are the busiest days for persons who sell cakes and would know the most about costing. (Wedding set-ups, birthday cakes out the door, etc.) I wouldn't expect a response in four hours.
Let everyone know the size of the cake, how you will be decorating it, what recipe/mix/icing you will be using. All these things factor into the cost of the cake. Have you added up all your ingredients yet? Adding up gas to drive to store, electricity, gas oven, etc. with this will give you the absolute minimum to recoup costs, without labor.
Tracy, I'm going to post what you PMed me so we can get the opinions o persons who sell their cakes. (I'm just a hobbyist.) Let me know if you want me to take it down.
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Well, it is a sheet cake with buttercream frosting. I will add a few fondant accents, but not many. It is a cake for a party that has 200 guests but they said it could feet 100 and they would just cut really small pieces. I have never charged for a cake before and don't have a clue how to do this.
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A few questions:
1. I'm assuming you're planning to do one cake layer? Ie, you won't have a filling layer and another cake on top of it?
2. Do you have a sheet cake pan already that you'll be using? What size is it?
Answer these here, again, so knowledgeable people can post. We'll get some sort of answer for you soon! No worries. 
In the meantime, you might peruse this:
http://www.wilton.com/cakes/making-cakes/baking-party-cake-2-inch-pans.cfm
Two 12x18's (ergo a 18x24), when cut in 2x2x2 (single layer) pieces, will yield 108 servings (cut will be cut into 9 rows by 12 columns). If they plan to cut these HALF that size to serve 200 people, they are going to have a cake that is 2" tall, with a width of 1" x 2".
That's not a piece of cake ... that's a sample! Of course they will also save money on plates and forks since a cake piece that size can just be popped in your mouth with no time for a plate or fork! 
I might ask them what they THINK a normal serving is. If they picture a big 'ole hunka cake that's cut in half, they're in for a surprise. Are they having other desserts?
Before I even get into pricing, I'd want to deal with this issue first. Because I'm telling you, the guests will NEVER say "Hostes didn't order enough cake." Nope .... they will ALWAYS say the cake maker didn't MAKE enough cake."
Ordering cake for 100 when they are expecting 200 guests (for a BABY SHOWER????? 
) is a big red flag that tells me no matter WHAT you charge them, they are going to be a big PITA about it. They sound like a grocery store bakery customer .... I'd send them there.
My attitude tends to be "Look .... if you're going to feed 200 people, this is what it's going to cost." If they don't want to buy enough food for their guests, then they need to trim their guest list.
Ordering cake for 100 when they are expecting 200 guests (for a BABY SHOWER????? ) is a big red flag that tells me no matter WHAT you charge them, they are going to be a big PITA about it. They sound like a grocery store bakery customer .... I'd send them there.
Agreed. These sound exactly like the kind of cheapskates who will freak out if you tell them "fair market value" for your custom cake, which is, from what I read here on CC, usually no less than $1.50 a serving and depending on location could be as high as $4.00/serving. They are thinking of $16 sheet cakes from Costco, which is also probably what they have planned for budget-wise.
If you decide to give them a quote, as the previous poster said, add up ALL your costs, including labor. Don't give away your time and talent. Be aware that even if you charged $1/serving (which would be a grand total of *gasp* no less than $100 
) you would probably only be close to breaking even on ingredients, supplies, and gas.
And also...? Inviting 200 people to a baby shower with enough cake for only 100 of them? Ruuuuuuuuuuude. 
Thank you so much for your help. I agree with all of you. I normally do carved cakes with fondant which is why I was totally shocked to have someone ask me for a normal sheet cake. My thought was exactly that.....why don't you just go to costco? I wanted to over charge it to make them realize that if they need a sheet cake, they should go elsewhere!!!
I charge $5/serving no matter what the cake shape is.. they's probably fall over if they heard my quote.
I agree with Debi that ordering cake for 1/2 of your guests is a HUGE red flag. Everyone attending should have a piece of cake waiting for them. The size serving that they will be handing out is a coffee sized serving which is 1/2 the size of a wedding serving. If you really don't want to do it just say no. Either that or tell them it'll be $1000.00 for cake for 200 like I would..
I'd charge at least $100 for the basic 1 layer sheet cake with the design extra. Call a couple of local Bakeries and ask them to price it for you, then you have an idea. Don't charges less than the bakery. Even if they say they can get it at Wal-mart or Kroger you can always ask them if they'd TASTED those cakes..lol. IMHO, the proof is in the tasting
I charge a straight $2/serving for my sheet cakes. That's a single layer, no filling, with border, writing, and a few flowers. So even if I'm only serving 100 people, that'll be $200 minumim. Once you get 2 layers and a filling in there, it's the same price as any other cake I sell. Oh - and that's with telling the customer that the serving size is 2x2x2.
OMG.....I have to post what the final result was. I ended up telling the client I didn't have enough time to do this cake because I was going to be making a FREE cake for my son's football team which her son is on. It was going to be a football helmet with 5 layers of cake. Since I told her I didn't have enough time to do the baby shower cake, she called the team mom and they decided NOT to have me make the team football cake and to purchase it from Costco AFTER I had already purchased all the supplies for the team cake which was due out next week. I am so outraged!!!! They turned down a FREE personalized cake for the team to purchase a Costco cake.
What do you want to bet that she wanted a "Deal" on her baby shower cake and felt slighted when you told her you didn't have time so she thought you wouldnt "Have Time" for the team's cake either... Okay, I may be overstepping the bounds here, but y not just tell her the truth?
Well, I was going to give her a price of $3.50 per slice for her baby shower cake. However, The football helmet cake was due on the 18th. She wanted the baby shower cake the following Friday. Normally, that isn't a problem except that I have 2 other jobs. I work with Farmers Insurance and I am also a Personal Trainer, Cycling, Water Aerobics teacher in addition to cake decorating. I am also getting certified to teach Kickboxing and Pilates that same week which only left me about 6 hours to make the baby shower cake. So, after careful consideration, I decided I shouldn't do the cake because of time constraints. Secretly, I also didn't want to, but I had no idea she would go to the team mom and cancel the FREE team cake in lieu of a costco cake.....gasp. Plus, once she told me not to make the team cake, I told her I was going to make that cake for another YAFL team and then she promptly called to tell me they decided they might LET me make the cake after all. I told them they placed me in a position where I purchased all the items for the cake and then they told me not to make it. Therefore, as a matter of principle I told them, I wasn't going to make it for them at all. 
I was really hurt 
because I know my son would want an extraordinary cake that his mother made. I am giving the cake to another team. 
.
How childish....Oh my, I would have flipped. The team mom is worse then the other lady to be so childish! And the only ones who suffer are the kids on the team because the mom's wanted to act in a child like manor.
I'm wondering if I would confront the team mom...mmmmmI probably would like to but be talked out of it by my husband.
I would ban that lady from ever ordering a cake from me or anyone else in town! Seriously...
That's why I rarely do sheet cakes. Everyone thinks that because it's a sheet cake and not a 3D or tiered cake that it's going to cost $29.95 for a full sheet!!
I torte all of my cakes...sheets included. With a sheet cake of mine you get three layers of cake and two layers of filling. Plus scratch icing, hand drawn, airbrushed or fondant decorations.
I honestly tell anyone who orders a sheet cake that if that's all they want, they can get it cheaper at Costco than through me.
You know what? Just do the cake. Even if she was being ugly about it, you be the bigger person and not let her get to you, or at least not let her know she got to you. Besides, the rest of the Team Parents probably don't know about this incident so you would be missing an opportunity to advertise for basically nothing. Also, your son is on that team and you don't want him to be shunned because of something going on with his mom..
Yes, that woman was out of line to go to the team mom to cancel your cake...but the team mom should have contacted you, since you were the one doing the cake, and it seems to me like the contact should have been between you two. I agree with the previous poster to do it anyway, if nothing else but to make your son happy.
In the future, if you are ever stuck on what to charge...go to Wilton's site and pull up their serving chart. Look at the servings, and that will let you know what pan you will need, etc. Then based on the number of servings, figure out a per serving rate and charge away!
I thought about doing it anyway, but I am normally quite a pushover and I don't want them to think they treat me poorly and I am just going to roll over and do it anyway. I never tell people what I think and I usually just get stepped on. I am really trying to stand up for myself on principle!!
I agree.....I am not going to do sheet cakes ever again either!!!! But, now I would like more advice on whether or not I should do the cake anyway. I could do it and not tell anyone I am bringing it......just show up with it???? Do you think I should or would that be rude?
Personally, I would not "just show up with it". Now there will be twice as much dessert, and it will turn into a "taking sides" kind of situation. Let's see where everybody's allegiance is. Oh, Mary-Alice is getting Costco cake, she must not like me....ad nauseum. 
I don't know. I would feel like I was being showoffy if I did that, but it might also bring some personal satisfaction as well.....hmmmmm 
I'm trying to take my son into consideration, but would also like personal satisfaction. However, I told my son when he got home from school that I wasn't going to be making his team cake. He was mortified to learn that I wouldn't be making it because he said I make THE BEST CAKES IN THE WHOLE WORLD. I told him thank you and then he asked where they were getting the cake from and I told him Costco......to which he replied..."WHAT.....are they crazy???? Those cakes Stink!!!" It made me feel good.
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