How many sheets of plywood do I need?
Dividing total part area by 32 square feet gives you a number that is almost always too low. Kerf, grain direction and the long skinny parts that only fit one way all eat into a sheet. The bookcases above are a good example. Each 72" side leaves a 24" offcut on its strip, and none of the 34 3/8" shelves fit in it. Whether those offcuts get used for anything decides the sheet count.
So lay it out. Enter every part at finished size, press Calculate, and read the sheet count off the result. If the last sheet is mostly empty, that is worth knowing before you load the truck. Sometimes a shelf 1/2" narrower gets you down a whole sheet. At $75.73 for a sheet of 3/4" birch, that adds up. See plywood prices by type for what each grade costs.
Real plywood sizes
Measure the sheet you actually bought. These are the sizes you will run into most:
| Sheet | Size to enter | Notes |
|---|---|---|
| Standard 4×8 | 96 × 48" | Most hardwood and construction ply. |
| Oversize 4×8 | 97 × 49" | Some MDF and melamine. Gives you room to trim. |
| Baltic birch | 60 × 60" | Sold as 5×5. Often cheaper per usable foot for drawer boxes. |
| Half sheet | 48 × 48" | Handy when the store will make one cut for you. |
"3/4" plywood is usually 23/32" thick and 1/2" is often 15/32". That does not change the layout, but it does change part sizes when one part sits between two others. Size your bottoms and shelves from the real thickness.
Grain on cabinet parts
On a 4×8 sheet the face grain runs the 8 foot way. Tick Grain on anything you will see: cabinet sides, doors, drawer fronts, the face of a bookcase. Leave it off for bottoms, fixed shelves inside a carcass, nailers and backs. Every part you leave free is a part the calculator can turn to fill a gap, and that is where most of the savings come from.
Breaking down a sheet on a small saw
A full sheet of 3/4" ply weighs 60 to 70 pounds. On a jobsite table saw you do not want to rip it at full length. The cut steps list the first cuts across the whole sheet first, so you can break it into pieces you can handle with a circular saw or track saw on the floor, then finish on the table saw. Use 1/8" kerf for a full-kerf blade and 3/32" for thin kerf. If you are not sure, 1/8" leaves you a little extra.