Cabinet Cut List Calculator: What the Numbers Come From
Search for a cabinet cut list calculator and you will find two different tools wearing one name. One turns a cabinet into a list of parts. The other takes a list of parts and works out how they sit on your sheets. This page is about what each of them is really doing with your numbers, so you can tell whether an answer is trustworthy before you cut into a sheet.
The short version
A cut list calculator is doing arithmetic on four inputs: the construction that decides part sizes, the width of the cut, the thickness of any edgebanding, and the stock you have to cut from. Get any one of those wrong and the list still looks perfectly reasonable. It only stops looking reasonable at the machine.
| Job one | Turn a cabinet into parts: name, quantity, material, thickness, finished size, grain, which edges get edgebanded, and which box each part belongs to |
|---|---|
| Job two | Arrange those parts on real stock, with the width of the cut and the direction of the grain accounted for |
| Kerf | The real width of the blade or the bit in the machine, measured rather than defaulted |
| Edgebanding | Comes off the finished size, so the printed number is the size to cut |
| Stock | Full sheets and the offcuts you already own, in the sizes you actually buy |
| The output | A parts list and a sheet layout, in a file the next station can read |
On this page
The two jobs one calculator does
The phrase covers two tools that solve different problems, and knowing which one you are looking at saves an afternoon.
A cut list generator starts at the cabinet. You give it a box, a construction and a set of sizes, and it gives you back every rectangle that box is made of. The interesting work is the arithmetic between the cabinet size and the part size, and that arithmetic is a set of decisions about how the box goes together rather than a single formula.
A sheet nesting calculator starts at the parts. It already knows the rectangles and it works out where each one goes on a sheet, how many sheets the job takes, and what is left. The interesting work here is packing, and it is a genuinely hard problem: fitting rectangles into a fixed area with the fewest sheets is the cutting stock problem, and it is solved by heuristics rather than by a formula that always wins.
Plenty of shops run the two separately, parts out of one program and nesting in another, and that works. The thing to watch is that the second answer goes stale the moment the first one changes. A cabinet that grew by 6 mm after you nested is a sheet you have already cut.
Where the part sizes come from
This is the part that separates a calculator you can trust from one that gives you a plausible number. A part size is not a property of the cabinet. It is a consequence of how you decided to build it.
Take a plain frameless base cabinet. Whether the sides run past the bottom to the floor or sit on top of it changes the height of the sides and the width of the bottom. Whether the back sits in a groove or lands on the back edges changes the depth of every horizontal part. Whether the top is a full panel or a pair of stretchers changes what is on the list at all. None of these are unusual choices. All of them move numbers.
So the first question to ask any cut list calculator is where it gets the construction from. If the answer is a fixed template, the parts it gives you are correct for somebody else's shop. If you can set the construction once and have the parts follow it, the list is describing what you actually build. Our companion guide, from a sketch to a cut list, works one right through by hand so you can see exactly which decision moves which number.
Two cabinets called Upper. Whatever tool you use, check that a part row names the cabinet it belongs to. A parts list without that column hands the bench two identical piles it cannot tell apart, and the mistake shows up at the end of the day rather than the start.
Kerf is a measurement, not a setting
The kerf is the width of material the cut removes, and it is the number people leave on whatever the tool shipped with. A default kerf is a description of somebody else's tooling.
Measure yours. A thin-kerf saw blade takes roughly 2.4 mm, which is a shade over 3/32 in. A standard full-kerf blade takes roughly 3.2 mm, or 1/8 in. On a CNC the kerf is the diameter of the bit in the spindle, so it changes the moment somebody swaps the bit, and a 6 mm bit takes nearly twice what a full-kerf blade does.
The reason it matters is that the error travels. Here is the same row of parts under two tools:
| Six parts at 400 mm each | 2400 mm of parts, and five cuts between them |
|---|---|
| At 3.2 mm kerf | Five cuts take 16 mm. Total 2416 mm, so it fits on a 2440 mm sheet length with 24 mm spare |
| At 6 mm kerf | Five cuts take 30 mm. Total 2430 mm, so it still fits, with 10 mm spare |
| Seven parts | 2800 mm of parts before a single cut is counted, so neither tool gets it out of one length |
Two things fall out of that table. The kerf is what decides whether the last part in a row makes it, which is why a wrong kerf shows up at the end of a sheet rather than the beginning. And the trim cut that squares the first edge costs another kerf plus whatever you trim, so a plan that counts only the cuts between parts is running slightly optimistic.
Edgebanding comes off before the cut
Two sizes live in every list and it is worth being clear which one you are reading. The finished size is what the part has to measure when it is done, edgebanding included, because that is the size the cabinet was drawn to. The cut size is what you cut at the machine, with the thickness of the band taken off each edge that gets one.
A part finished at 600 mm with 1 mm edgebanding on one long edge is cut at 599 mm. Band both long edges and it is cut at 598 mm. That is small enough to ignore once and impossible to ignore across a run of drawer fronts stacked in one opening, where the gaps between them are the thing anybody looks at.
So the row has to say which of the four edges get edgebanded, edge by edge, rather than carrying a yes or a no for the part. Thin bands around 0.45 mm to 1 mm are what most cabinet interiors get; thicker ones from 2 mm up go where hands land. Which to use where is its own guide, and the definition on its own is in the glossary.
From a parts list to a sheet layout
Once the rectangles are right, the second calculator earns its keep by turning them into sheets. Four things decide whether its answer is any good.
| Your real stock sizes | A metric 4 by 8 panel is 2440 by 1220 mm, which is 96 1/16 in by 48 1/32 in. A plan that quietly rounds that to 96 in is planning against a sheet that does not exist |
|---|---|
| Your offcuts | The rack beside the machine is inventory. A nester that can be told about it fills the small parts out of stock you have already paid for |
| Grain | A part with a grain direction may not be turned to make it fit, which costs yield and is not negotiable on a finished face |
| How the machine cuts | A panel saw cuts edge to edge, so the layout has to be made of full-width strips. A router can drop in anywhere, so it can nest shapes a saw could never separate |
That last row has a name. An edge-to-edge layout is a guillotine cut pattern, and it is a real constraint rather than a preference: a nest that ignores it produces a beautiful drawing that a panel saw cannot cut. What the constraint does to your yield, worked through with numbers, is the sheet nesting guide.
Four things worth checking
Whatever tool you land on, these four take about five minutes together and they catch most of what goes wrong.
| 1. Is the kerf yours? | Open the setting and compare it to the blade or the bit currently in the machine |
|---|---|
| 2. Is the printed size the cut size? | Find one banded part and check the number is the finished size less the band, not the finished size |
| 3. Does every row name its cabinet? | Sort the list by cabinet. If you cannot, the list is a pile of rectangles |
| 4. Is the sheet size the sheet you buy? | Check the stock entry against the label on the rack, in the unit you buy in |
A fifth one, if you are choosing between tools rather than checking one: cut a single test part at the size it gives you and measure it. One part costs a few minutes and it settles the argument that a spreadsheet cannot.
How it works here
CabDesign does both jobs in one place, which is the reason the two halves cannot drift apart on you.
The Designer holds the room and the cabinets, drawn in floor plan, in elevation and in 3D. Because the parts come out of the geometry you drew rather than being counted by hand afterwards, a cabinet you resize on Tuesday is a parts list that already knows.
The Cut List Optimizer takes it from there. It nests in an edge-to-edge cut pattern a panel saw can follow, it holds grain direction on the parts that need it, it takes the width of the cut and the edgebanding into account, and it reaches for your offcuts before it opens a new sheet. The stock it plans against comes from the Materials Library, so the thickness, the sheet size and the grain belong to the material and travel with it instead of being retyped per project.
Parts can come from somewhere else too. Paste rows straight in, tab separated or comma separated, with a header of Label, Width, Length, Qty, Type and Grain. Your own stock list comes into the Materials Library as a CSV.
What leaves is three files, each one versioned so the mapping the receiving program remembers keeps working: a spreadsheet CSV with every part as a row, a cut station parts list with one row per distinct cut sorted by material then longest first, and a DXF drawing of the nested sheets that opens in any CAD or DXF viewer, including the CAM software a CNC shop already has.
The Optimizer keeps your project against your account, so it asks you to sign in. That is free during the open beta and there is no card; the pricing page carries the dates and what happens afterwards. If you want arithmetic without an account at all, the free tools page has five that run entirely in your browser.
Try it on a real job. Paste a parts list into the Cut List Optimizer and see what it does with your sheet sizes and your offcuts.
Common questions
What does a cabinet cut list calculator do?
Two jobs, and it is worth knowing which one you are asking for. The first turns a cabinet into a list of rectangles: every part, its finished width and length, the material and thickness it comes out of, how many, and which box it belongs to. The second takes that list and works out how the rectangles sit on the sheets you own, with the width of the cut and the direction of the grain accounted for. A tool that only does the first hands you a parts list. A tool that does both hands you a parts list and a sheet layout you can cut from.
Is a cut list generator the same as a sheet nesting calculator?
They are the two halves of the same trip. A cut list generator produces the parts. A sheet nesting calculator arranges those parts on stock and tells you how many sheets it takes. You can run either alone, and plenty of shops do: parts out of one program, nesting in another. The reason to want them joined up is that a change in the first silently invalidates the answer from the second, and a cabinet that grew by 6 mm after you nested is a sheet you already cut.
What kerf should I enter?
The real width of what is cutting, measured off your own machine rather than taken from a default. A thin-kerf saw blade takes about 2.4 mm, which is 3/32 in. A standard full-kerf blade takes about 3.2 mm, or 1/8 in. On a CNC the kerf is the diameter of the bit in the spindle, so it changes the moment the bit does. The error is small per cut and it accumulates along a sheet, which is why the last part in a row is where a wrong kerf shows up.
Does the calculator take edgebanding off the part size?
It should, and it is worth checking which way round yours works. The size that matters at the end is the finished size, edgebanding included. The size that matters at the machine is the cut size, with the thickness of the band taken off each banded edge. A part finished at 600 mm with 1 mm edgebanding on one long edge gets cut at 599 mm. The Cut List Optimizer here takes kerf and edgebanding into account when it nests, so what it prints is the size to cut.
Can I bring parts in from a spreadsheet?
Yes. Paste part rows straight into the Cut List Optimizer, tab separated or comma separated, with a header row of Label, Width, Length, Qty, Type and Grain. Your stock comes from the Materials Library, so thickness, sheet size and grain travel with the material rather than being retyped per project, and the Materials Library takes a CSV of your own stock list.
Keep reading
Sources & references
The packing problem and the guillotine constraint are named the way the literature names them, so the terms are checkable. The kerf figures are the common ranges for the tooling described and are worth confirming against your own machine rather than taken on trust. Every claim about what CabDesign does was read out of the shipped code, with the file and line in an HTML comment beside it in this page's source.
- Kerf (what the cutting tool removes, and why it is planned rather than absorbed)
- The cutting stock problem (why nesting is solved with heuristics rather than one formula)
- Guillotine cutting (the edge-to-edge constraint a panel saw enforces)
- AutoCAD DXF (the neutral drawing format the nested sheets export as)
- Architectural Woodwork Institute, manufactured wood casework standards (the specification tradition governing the finished part)
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