Lumber Cut List Optimizer
Turn cut lengths and stock into low-waste boards
Lumber cut list and waste optimizer FAQ
How should I enter my cut lengths?
Keep it simple: list each finished piece length in your chosen units, separated by commas or new lines. If you need multiple identical pieces, use a small multiplier like 48x4 to mean “four pieces at 48”. The calculator expands these into individual cuts before packing them into boards.
Why is everything in inches or millimetres, not feet?
To keep the form small and the math reliable, the calculator works in a single base unit: inches for US jobs, millimetres for metric. You can still think in feet or metres—just convert your stock and cut lengths to inches or millimetres when you type them in (for example, 8 ft → 96 in, 3.6 m → 3600 mm).
What is saw kerf and why does it matter?
The kerf is the width of material removed by the blade each time you cut. Ignoring it can leave you a little short on the last piece. This tool assumes every cut uses up its length plus one kerf, which slightly overestimates waste and keeps you on the safe side.
How does the optimizer actually place cuts?
The calculator uses a simple first-fit decreasing approach: it sorts cuts from longest to shortest, then drops each one into the first board where it fits once kerf is included. It’s fast, easy to understand and usually close to optimal for small woodworking and framing projects.
Is this always the mathematically perfect solution?
No. The underlying “cutting stock” or “bin packing” problem is NP-hard, and finding an absolutely minimum-waste pattern can be complex. This tool trades perfection for a clear, practical pattern that most people can follow and tweak in the shop.
Can I mix multiple stock lengths in one run?
This version assumes a single stock length. If your yard sells 8, 10 and 12 ft boards, you can either run the calculator separately for each length or use the results here as a baseline, then ask your supplier whether swapping in a few longer or shorter boards would trim waste even further.
What if some cuts are longer than my stock length?
The tool flags any cut that is longer than the stock length as invalid, because that piece physically cannot come from a single board. In practice you would need to change the design, join shorter pieces, or move up to a longer stock size.
Should I still sketch patterns on paper?
For bigger jobs, yes. Use this calculator to get board counts and a starting pattern, then refine on paper or in CAD to respect grain direction, defect locations, crown orientation and any structural or aesthetic constraints the project needs.
How to use this lumber cut list optimizer
This calculator takes a simple cut list and a single stock length, then suggests how to pack pieces into boards to reduce waste and offcuts. You just pick units, stock length and kerf, paste your cut lengths and read off the plan.
1. Choose units and stock length
Start by picking whether you want to work in US inches or metric millimetres. In US mode, type an 8 ft board as 96 in; in metric, type a 3.6 m length as 3600 mm. Use the stock length box for the board you expect to buy most of.
2. Enter saw kerf (or leave the default)
Each saw blade removes a little material. If you know your blade kerf, type it in (for example 0.125 in or 3 mm). If you leave the box blank, the calculator assumes a typical value for the chosen unit so that last piece isn’t accidentally too short.
3. Paste or type your cut list
In the Cut list box, list every finished piece length you need. You can either:
- Enter individual pieces: 32, 32, 48, 60, or
- Use multipliers: 32x2, 48x1, 60x3.
Commas and new lines both work, so you can paste directly from a spreadsheet or notes app and keep the form small.
4. Read board counts, waste and patterns
Hit Optimize boards & waste to see:
- Total boards required at your chosen stock length.
- Total stock purchased, total cut length and overall waste percentage.
- A board-by-board cut pattern such as “Board 1: 60 + 36 (waste 0.5 in)”.
You can reorder cuts or tweak patterns by hand, but the calculator gives you a solid head start.
5. Copy the summary into your project notes
Use Copy summary to paste the results into shop notes, a cut ticket or an email to your supplier. From there you can round up boards, mark special pieces and consider whether saving an extra board is worth extra joints or layout complexity.
Treat this as a fast, transparent helper for small projects. If you’re optimizing expensive hardwood, engineered members or anything structural, combine this tool’s output with a full drawing, grain/defect layout and any instructions from your engineer or building designer.
How the lumber cut list optimizer math works
Under the hood, this calculator is a small, friendly version of the classic one-dimensional cutting stock / bin packing problem. It uses simple, explainable steps rather than heavy optimisation libraries so you can follow the numbers.
1. Convert everything into a single base unit
Depending on your choice, all values are converted into either inches or millimetres:
US mode: values stay in inches.
Metric mode: values stay in millimetres.
Stock length, kerf and each cut are kept in the same unit so the later comparisons are straightforward.
2. Expand the cut list into individual pieces
The text in the cut list box is split on commas and new lines. Tokens like 48x3 are expanded into three individual cuts of length 48. Tokens that cannot be parsed, or any cut longer than the stock length, trigger a validation error instead of silently producing nonsense.
3. Apply a simple first-fit decreasing strategy
All cut lengths are sorted from longest to shortest. For each cut:
- The tool checks existing boards in order and drops the cut into the first board where it fits once kerf is included.
- If no existing board has enough remaining length, a new board is started.
To stay conservative, each piece is treated as using length + kerf of stock. That means actual waste will usually be slightly better than reported, not worse.
4. Calculate waste and efficiency
Once every cut is placed, the calculator sums:
- Total stock purchased: boards × stock length.
- Total cut length: sum of all finished piece lengths.
- Estimated kerf loss: number of cuts × kerf.
Board-level waste is:
Waste per board = stock length − (total cut length + kerf per cut on that board)
Overall waste percentage is:
Waste % = (total waste ÷ total stock) × 100
This approach keeps the optimiser fast, predictable and easy to sanity-check with a pencil. If you ever need more aggressive optimisation, you can still feed the same cut list into a specialist cutting-stock solver or panel optimizer and compare results.
References and further reading on cut lists and waste
These resources discuss cut list optimisation, kerf and cutting-stock math in more depth:
- Wikipedia — Cutting-stock problem — background on one-dimensional cutting stock and bin packing.
- CutList Optimizer — online tool for optimising sheet and board cutting patterns.
- CutList Plus fx — desktop software for lumber and sheet goods cut lists and layouts.
- The Spruce Crafts — Definition of kerf in woodworking — plain-language explanation of saw kerf and why it matters.
Use this calculator as a quick helper and these references when you want to dive deeper into cutting-stock strategies and tooling.