Cut list calculator for plywood and melamine sheets

How the cut list is laid out

The calculator places your pieces on the sheet in strips, with every cut running from edge to edge, and counts the sheets you need. These are guillotine cuts, the kind a table saw, a track saw or a panel saw makes: each cut goes all the way through the piece in your hands.

1. Usable area. The edge trim comes off all four sides. With no trim, a 4 × 8 sheet stays 96 × 48 in.
2. Order. Pieces are sorted from tallest to shortest. If rotation is allowed, any piece can turn 90 degrees.
3. Strips. The first piece opens a strip as tall as itself. Pieces that fit go next to it, and shorter pieces stack in the same column when the strip is tall enough.
4. Kerf. Between two pieces we leave the width of the blade, the wood that turns into sawdust.
5. Sheets. When a piece finds no room, a new strip opens, and when the sheet is full a new sheet starts.

We try strips along the length and along the width of the sheet, with the pieces both ways, and keep the layout with the fewest sheets, then the fewest cuts. The method is simple and always gives the same answer. Dedicated cutting software sometimes squeezes in one more piece, but this layout can really be cut, in the order you see it. Waste is everything you buy that does not become a piece: trimmed edges, sawdust and offcuts.

Worked example: a 36 × 72 in bookcase

A bookcase 36 in wide, 72 in tall and 11 1/4 in deep, in 3/4 in plywood: 2 sides at 72 × 11 1/4 in and 5 shelves (top, bottom and 3 shelves) at 34 1/2 × 11 1/4 in, that is 36 minus two 3/4 in sides. One 4 × 8 sheet, 1/8 in kerf, no edge trim. These are the values the calculator opens with in US units.

• Laying every piece lengthwise in strips along the 8 ft side takes 2 sheets: a side uses 72 in and leaves 23 7/8 in, too short for a shelf, and a fifth strip of 11 1/4 in does not fit in 48 in once the kerfs are counted.
• The calculator also tries the other layouts and keeps the one with 1 sheet and the fewest cuts. Its first cut goes across the sheet at 72 in. In that part the two sides and four shelves fit in four strips, and the fifth shelf goes upright in the 23 7/8 in left at the end.
• Result: 1 sheet, 11 cuts.
• Waste: the pieces cover 24.73 ft² of 32 ft², so 22.7%. A full-width offcut of 12 1/2 × 48 in is left at the end of the sheet.

If the plywood has a grain you want running the same way on every piece, untick rotation: the same bookcase then needs 2 sheets, with 61.4% waste.

In the UK, with metric units: a bookcase 80 cm wide, 200 cm tall and 30 cm deep (2 sides 200 × 30 cm, 5 shelves 76.4 × 30 cm) fits one 2800 × 2070 mm melamine board with a 4.4 mm kerf and a 10 mm trim, with 59.5% waste and a 278 × 113.7 cm offcut.

How many shelves you get from a 4 × 8 sheet

Identical shelves the calculator fits on one 96 × 48 in sheet, with a 1/8 in kerf, no trim and rotation allowed.

Shelf (depth × length)	Per sheet
7 1/4 × 36 in	15
9 1/4 × 36 in	12
11 1/4 × 24 in	14
11 1/4 × 30 in	12
11 1/4 × 36 in	10
11 1/4 × 48 in	8
15 3/4 × 36 in	7
23 1/4 × 36 in	5

In the UK, on a 2440 × 1220 mm sheet with a 4.4 mm kerf and a 10 mm trim, the calculator fits 12 shelves of 60 × 30 cm, 10 of 80 × 30 cm and 7 of 100 × 30 cm.

Sheet sizes, kerf and edge trim

Common sheet sizes:

• Plywood in the US: 4 × 8 ft, or 48 × 96 in, is the standard sheet.
• UK: MDF comes as 2440 × 1220 mm, the metric 8 × 4.
• Melamine faced chipboard (MFC): manufacturers such as Cleaf make it in 2800 × 2070 mm boards.

The kerf depends on the blade. A full-kerf 10 in table saw blade cuts about 1/8 in, which is why we start there. Panel saw blades in the Freud LSB X catalogue cut 4.4 mm, about 11/64 in. If a store or a shop cuts your sheet, ask for the kerf of their saw.

The edge trim is there because the edges of a full sheet are not always clean. Egger's data sheet for melamine faced board allows edge chipping of up to 10 mm on full boards and 3 mm on cut sizes, so the metric calculator starts with 10 mm per edge. On a 4 × 8 sheet we start at 0; if the edges are dinged, 1/4 in per edge leaves a usable 95 1/2 × 47 1/2 in.

Common mistakes

• Forgetting the kerf. Without kerf, 32 squares of 12 × 12 in come out of a 4 × 8 sheet. With a 1/8 in blade you get 21, because 4 strips of 12 in plus 3 kerfs need 48 3/8 in.
• Rotating pieces that have a grain. On veneered plywood or wood-grain melamine the grain should run the same way on every visible piece. Untick rotation and each piece keeps its length along the length of the sheet.
• Getting the shelf length wrong. Shelves between two sides are as long as the bookcase is wide minus two sheet thicknesses: with 3/4 in sides, a 36 in bookcase has 34 1/2 in shelves.
• Measuring from a damaged factory edge. If the first edge is chipped or out of square, every piece after it follows the error. Keep a trim, even a small one.
• Throwing away the offcut. The waste percentage looks high, but much of it is often one whole offcut. The shopping list gives the size of the one left on the last sheet.