Calculator
Cut list and board estimator
Type the pieces you need, one line each, and the length of the boards you will buy. The tool groups the pieces onto boards, shows what goes on each one and tells you how many boards to buy. Nothing leaves your device.
Worked example (shown when scripts are off): four 36 inch pieces, two 24 inch pieces and three 17.5 inch pieces from 96 inch boards. Two 36s and a 24 do not quite fit on one board once the saw cuts are counted, so the pieces spread over 3 boards.
Before you decide
Check the real length of the boards at the store, because the length on the label is not always the length you get, and look for knots, bows and damaged ends you will need to cut away. Add a spare board for any piece that has to match the grain or color of its neighbors. Measure twice, mark, and cut only after the layout is final.
How the layout works
The tool uses a simple method called first-fit decreasing. It sorts the pieces from longest to shortest and puts each one on the first board that still has room. Each piece takes up its own length plus one saw kerf, the thickness of metal removed by the blade. A typical circular saw or hand saw blade removes roughly one eighth of an inch, which is why the default is 0.125. If your blade is thicker or thinner, change the number.
When a piece is exactly as long as the board, no kerf is added for it. The spare-board option adds one extra board for every 10 you need, rounded up, to cover a miscut or a bad board. That 10 percent figure is our own planning choice, not a published rule.
Worked example
You need four 36 inch pieces, two 24 inch pieces and three 17.5 inch pieces from 96 inch boards. Two 36 inch pieces and the kerf use 72.25 inches, which leaves 23.75, not quite enough for a 24 inch piece (24.125 with its kerf). So the 24s go together with the shorter pieces. The result is three boards, with the layout printed for each.
Why it is not always the fewest boards
Finding the true minimum number of boards is a hard puzzle called bin packing. The longest-first method is quick and usually close to the best answer, but a different order can occasionally save a board. If the result is one board over a whole number of boards, try swapping a piece length by a fraction of an inch, or look at whether a longer board length would suit better.
What it does not do
- It does not know about grain direction, color match, knots or angled cuts. Mitres use more length than a straight cut, so add extra for them.
- It treats every board as the same length and does not subtract damaged ends.
- It does not handle sheet goods such as plywood, where pieces are laid out in two directions.
- It does not price the boards. Multiply the count by the price per board at your supplier.
Wear eye protection and follow the saw maker's instructions when you cut. This page is general information, not professional advice.
Where this comes from
This tool is plain arithmetic, so there is no outside standard behind it. The method is first-fit decreasing, a well-known textbook heuristic for the bin-packing problem. The one eighth inch kerf is a typical default, not a rule, so measure your own blade or check its packaging. The code was run against sample cut lists, including exact fits, pieces that are too long and badly typed lines, and the results were compared with hand calculations.