Boards or sheets
- Boards · lengths is for parts cut to length from stock of one width — rails, legs, trim, shelf cleats. Enter the stock length, the kerf, any trim and each part’s length and quantity. Width is not considered: rip the stock to width first.
- Sheet goods · panels is for rectangles cut from plywood, MDF or other panels. Enter the sheet’s width and length, the kerf and each part’s width, length and quantity, and say for each part whether its grain may be turned.
How to use it
Laying out a cut list
Measure the stock
Boards: the usable length, in inches. Sheets: width and length — 48 × 96 in for a full 4 × 8 ft sheet. Measure the actual piece; sheet sizes vary slightly.
Set the kerf
The width of the saw cut, typically 1/8 in for a full-kerf table-saw blade and less for thin-kerf and hand saws. Check the blade.
Add trim (boards)
Length to cut off the stock first — an end check, a snipe, a rough end. It counts as waste.
List the parts
Lengths for boards; width, length and quantity for sheets. Fractions such as 11 1/4 are accepted.
Lock the grain where it matters (sheets)
Tick “Keep grain along the length” for parts whose face grain must run with the sheet’s length — cabinet sides, doors, visible panels. Unlocked parts may be turned 90° to fit.
Reading the layout
- Each board or sheet is drawn to scale with its parts labelled and sized. A part marked ↻ has been turned across the sheet.
- Hatched areas are unused stock — offcuts you may still use for smaller parts.
- The readouts give the number of boards or sheets, the area or length of parts, and the waste as a percentage of the stock used, kerf and trim included.
- A part that cannot fit is reported, not dropped: one longer than the stock, or one that only fits turned when its grain is locked.
How the layout is worked out
Finding the best possible layout is a hard combinatorial problem, and the calculator does not claim to solve it. It uses an efficient packing heuristic that gives good, repeatable layouts quickly; another arrangement can occasionally use one board or sheet fewer.
The two methods
- Boards
- First-fit decreasing: parts are sorted longest first, and each goes on the first board with room for it plus a kerf; a new board is started when none has room. Trim comes off each board before any part.
- Sheets
- Guillotine packing: each part goes into the free rectangle it fits most snugly (best short-side fit), and the space left is split by one straight cut across the sheet, so every layout can be cut with edge-to-edge rips and crosscuts. Each part is allowed one kerf on its width and length. Parts are placed longest side first, then by area; grain-locked parts are never turned.
Note— Grain direction
The sheet’s grain is taken to run along its length, as it does on most plywood. If yours runs the other way, enter the sheet’s width and length swapped. MDF and particleboard have no grain: leave every part unlocked.
Worked example
The sheet mode opens with a small cabinet’s parts on one 48 × 96 in sheet with a 1/8 in kerf: two sides 23 1/4 × 30 in and four shelves 11 1/4 × 34 in, all grain-locked, plus three 16 × 16 in blocks that may turn. The parts total 25.6 sq ft, well under the sheet’s 32 sq ft, so an area count says one sheet. The layout says two: the shelves and sides fill the first 64 in of the sheet, and only two blocks fit across the 48 in strip that is left — three blocks and their kerfs need 48 3/8 in. The third block goes on a second sheet.
That is the gap between counting area and laying out parts. Narrow the blocks to 15 3/4 in and all three fit on one sheet.
Limits
- The layout is a plan, not a cutting order. Work out which cuts to make first so each piece can be supported on the saw.
- Edges are taken as square and straight. Allow for jointing or trimming a factory edge by entering a slightly smaller sheet or board.
- Defects, figure and colour matching are yours to judge; the calculator sees only rectangles.
- For a quick count of sheets before you list every part, the plywood calculator estimates from area alone. To buy solid wood for the boards mode, the board foot calculator gives the volume to order.
About this calculator
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