Free timber cut list calculator. Turn the pieces you need into the stock lengths to order and a cut plan, allowing for saw kerf and offcuts.
This calculator takes the pieces you actually need and packs them into the stock lengths your merchant sells, so you order lengths rather than lineal metres. It gives you a cut plan, the offcuts, and the pieces that will not come out of anything on your list.
Twenty pieces at 2500mm is fifty lineal metres, so fifty metres looks like the right order. It is not. A 2500mm piece only comes out of a 6.0m length twice, leaving 997mm each time, so fifty metres of stock does not contain twenty of those pieces, and you find out on site.
The lineal-metre total is arithmetically correct and practically short every time the piece length does not divide the stock length. This packs the actual pieces into actual lengths instead, which is the only way the number comes out right.
It is first-fit-decreasing, the standard method for this kind of problem: sort the pieces longest first, and put each one into the first opened length it still fits. Then every length is shrunk to the shortest stock that still holds what went into it, so a length carrying one short piece is not ordered as a 6.0m with most of it thrown away.
It is a strong answer rather than a provably optimal one. Packing lengths optimally is a genuinely hard problem, and the last percent is not worth a plan you cannot read off the page.
The saw kerf is charged between pieces and not before the first, which is the detail that decides real cases: two 3000mm pieces do not both come out of one 6.0m length, and the plan says so rather than letting you discover it at the saw.
The cut plan lists every length and what comes off it, longest cut first. Offcuts above a threshold you set are listed separately, because a 900mm drop is stock and a 40mm drop is rubbish, and the difference matters when you are pricing the next job.
A piece longer than every stock length you entered is called out rather than quietly dropped from the count. Add a longer length, or plan a join.
Nothing here knows what your merchant stocks today, what is in the yard, or what a length costs. The default lengths on the page are a starting point to edit: CostMate does not supply stock lengths.
Confirm stock lengths, grade and availability with your merchant before ordering, and check the cut plan against your own allowances for docking and defects.