What are your sales projections for 16, 14, and 12 pizzas? What is your dough management going to entail?
If memory serves, a typical hand-tossed crust is going to require 1 tray for every 6 16", 8 14" and 12 12". If you’re planning to hold the dough for a day, you need twice as many boxes as the calculations above suggest. Additionally, that ASSUMES that you’ll have all used dough boxes washed before you begin dough for the third day. This would normally require that the night shift wash the dough boxes.
So, let’s use round numbers of 100 dough boxes per day.
day 1 requires 100, but dough won’t be used until day 2. Therefore, you need day 2’s fresh dough to go into an additional 100 dough boxes. By the end of day 2, you’ve used all of day 1’s dough. All dough boxes are washed, and on day 3, you re-use those boxes. Make sense?
I like to see 1-2 weeks of pizza boxes in the store. This gives you room for shipment delays and such. This, of course, assumes you’re not using custom boxes, which would normally require a larger purchase. Cardboard draws “critters”, so be aware of that.
Screens are pretty easy. I’d go with 3x what the ovens can hold, in proportion to your expected sizes. If you’re plans include 16" as your most popular size (all specials will include 16"), and your oven will hold 8 in the cooking chamber, you need 12 (2 exited, 2 on the belt waiting to enter). Multiply by 3 to allow for the first 12 to cool down while the 3rd 12 are in the oven. Make sure your oven tender plans accordingly so there are two stacks under the cut table which are cool and warm so the make line doesn’t grab hot screens. Naturally, you need to add the number of pre-made skins you expect to have on hand at the busiest time. If you plan to have 30 skins in racks on Friday night, add 30 to the 36. Do the same for 14" and 12", but account for the expected number of those pies to actually be ON the belt at any given time. You don’t expect to have an oven full of 12" pies unless you have a special on that size.