About the Cut List Optimizer
This cut list optimizer turns a list of parts into a cutting plan. In board mode it packs lengths into stock boards (2×4s, dimensional lumber, trim, dowels, pipe or aluminium bar); in sheet mode it lays out rectangular parts on plywood, MDF or melamine sheets. It tells you how many boards or sheets to buy, which parts to cut from each, how much material is wasted and what the stock will cost.
Enter one part per line as “length x quantity” for boards or “length x width x quantity” for sheets, in any consistent unit. The saw kerf — the width of material the blade turns to dust — is subtracted after every cut, so the plan is realistic for a table saw, mitre saw or track saw.
Boards are packed with the first-fit-decreasing method: longest parts first, each into the first board with room. Sheets use a rip-then-crosscut layout: parts are grouped into full-length strips ripped across the sheet width, then crosscut to length — the way most people actually break down plywood on a table saw. The results are very good but not guaranteed optimal; compare with the theoretical minimum shown.
With the default inputs, the boards / sheets needed is 6. Change any value above to recalculate instantly.
How to use the cut list optimizer
- 1Choose boards for lengths of lumber or sheet goods for plywood and MDF.
- 2Enter the stock size and your blade’s kerf in the same unit as your parts.
- 3List each part on its own line: length x qty, or length x width x qty.
- 4For sheets, untick rotation if the grain direction matters.
- 5Read the stock count and follow the cutting plan board by board or sheet by sheet.
Formula and method
Board mode uses first-fit decreasing (FFD), a classic bin-packing heuristic: sort parts from longest to shortest, then put each into the first board that still has room, opening a new board only when none does. After each cut the kerf is subtracted from the remaining length. FFD is proven never to use more than about 11/9 of the optimal number of boards (plus a small constant), and on typical cut lists it often matches the optimum.
Sheet mode uses a two-stage guillotine layout: parts are sorted by width, ripped into strips that run the full sheet length, and each strip is crosscut into parts first-fit. Strips are stacked across the sheet width, with a kerf between each. The theoretical minimum ignores kerf and layout, so the real plan can need one more board or sheet.
- Σ part sizes
- Total length (boards) or area (sheets) of all parts
- stock size
- Board length, or sheet length × width
- kerf
- Material removed by each saw cut
Worked examples
Shelving parts from 8 ft boards
The 21 parts total 496", so at least 496 ÷ 96 = 5.17 → 6 boards are needed. Longest-first packing gives two boards of 36 + 36 + 20, two of 28 + 28 + 28, one of 20 + 20 + 20 + 14 + 14 and one of 14 × 4 — six boards, 86% yield, $48 of lumber.
Picture frame rails from 6 ft moulding
Four 22" and four 16" rails total 152", and 152 ÷ 72 = 2.11, so three lengths are unavoidable. The plan cuts 22 + 22 + 22 from the first, 22 + 16 + 16 + 16 from the second and one 16" rail from the third, leaving a long offcut for the next frame.
Four 23 7/8" shelves from one 8 ft board
Four 23.875" parts total 95.5", and the three cuts between them lose 3 × 0.125 = 0.375", so 95.875" of the 96" board is used — they just fit on one board with 1/8" to spare. At 24" each they would not fit.
Cabinet parts on 4×8 plywood
Four 30×16 sides, two 46×16 shelves and six 22×11 drawer parts total 4,844 sq in — more than one 4,608 sq in sheet — so two sheets ($110) are needed. The 16" parts are ripped into strips first, then the 11" drawer parts share the remaining width.
Why kerf matters: eight 24" squares from one sheet
Eight 24" squares have exactly the area of a 48×96 sheet, but each 1/8" cut means only three squares fit along a 96" strip and only one 24" strip fits across the 48" width. The plan needs three sheets — cut the parts to 23 7/8" and they all fit on one.
Frequently asked questions
How does a cut list optimizer work?+
It solves a packing problem: fit all your parts into as few boards or sheets as possible. This tool sorts parts largest-first and places each into the first piece of stock with room, subtracting the saw kerf after every cut.
What is saw kerf and why does it matter?+
Kerf is the width of wood the blade removes, typically 1/8" (3.2 mm) for a full-kerf table saw blade or 3/32" for thin-kerf blades. Ten cuts on one board lose over an inch, which can push the last part onto another board.
How many sheets of plywood do I need?+
Add up the area of all parts and divide by the sheet area (4,608 sq in for a 4×8 sheet) for a lower bound, then lay them out. A real layout usually needs more than that because of kerf, grain direction and leftover strips that are too narrow to use.
Should I let parts rotate on plywood?+
Rotation helps the layout, but on veneered plywood the face grain should usually run the same way on visible parts such as doors and cabinet sides. Turn rotation off and enter those parts with the length along the grain.
Should I buy extra boards?+
Yes — buy at least one spare board or sheet for knots, warps, splits and measuring mistakes, especially with construction lumber where some boards will have defects at the ends.