Cut List Optimizer

How to measure

Measure each finished part in the orientation you want to cut it. For a shelf, the length is the long side and the width is the depth. Write the name you want on the diagram, then the quantity. A quantity of 2 creates two identical pieces.

Stock length for a board is the usable board you buy, such as 96 inches for an 8 foot 2x4. For plywood, enter the sheet length and width. A standard sheet is 96 inches by 48 inches. If the mill edge is damaged, set an edge trim. Trim is removed from both ends and, on a sheet, from both sides. A trim of 1/4 inch shortens a 96 inch board to 95.5 inches.

Kerf is the slot the blade removes between two parts. It is not added before the first part. Four 24 inch parts on a 96 inch board with a 1/8 inch kerf need 96.375 inches, so they do not fit on one board. The same parts with a 0 kerf do fit.

If a part is longer or wider than every sheet after trim, the layout stops and names that part. Lower the quantity limit when you only have a few boards on hand. Leave the quantity blank when the yard can supply as many as the layout needs.

Formula

Each linear board has a usable length of stock length minus two times the edge trim. The first part on that board uses only its length. Every later part also uses one kerf. The pieces on one board must satisfy that sum. With 30 pieces or fewer, the search tries packings and keeps the one with the fewest boards. Above 30 pieces it starts from first fit decreasing and moves parts between boards until the time budget ends.

A sheet is packed with guillotine cuts: each cut goes across one rectangle. The search tries several placement and split rules and keeps the layout with the fewest sheets, then the largest single offcut. A locked part cannot rotate. Yield divides placed material by usable stock.

Four 36 inch parts and four 24 inch parts, cut from 96 inch boards with a 1/8 inch kerf, need 3 boards. First fit decreasing would buy 4.

Common mistakes

• Forgetting the kerf, so a layout that looks exact on paper does not fit on the saw.
• Locking the grain on a part that only fits when it is turned.
• Entering the nominal board width as the sheet size. A 2x4 is a linear board, not a 4 inch sheet.
• Setting a quantity limit lower than the number of boards the parts require.