A client wants enough cake to feed 250 people. She agreed for part of it to be in sheet cakes . This is for a wedding reception. What sizes of cakes would you suggest? This is only my third cake and the biggest so far. A little nervous!

What design have you agreed on?        You need to take a look at the chart on the Wilton site to see the many different ways to go   That chart is considered the “industry’s standard” for # of servings each size yields.   There are many different ways to go with a request like that   What size pans do you have?  Are you willing to buy more/different pans?  As you can see you need lots more information before your ? can be answered 

I agree with Kakeladi. Maybe do a standard 3 or 4 tiered cake for the cake table with some cupcakes (or not). Have the sheet cake(s) at the venue's kitchen so they can serve the guest from them.