How to Read a Cutting Diagram (and Avoid Expensive Mistakes)

A cut list optimizer turns your parts list into a colorful map of rectangles inside a sheet. That map is called a cutting diagram. Read it correctly and you'll glide through a 40-part cabinet job in an hour. Read it wrong and you'll cut parts that don't fit, ruin a sheet of plywood, and have to start over.

Here's how to read every element of a typical cutting diagram, plus the cut sequence that experienced shops use.

The basics

A cutting diagram shows:

The stock sheet - usually drawn as a large outlined rectangle.
The parts - colored rectangles inside the stock, labeled with part name and dimensions.
Waste - the unfilled area, usually shown with a hatched or grayed-out fill.
Kerf gaps - narrow strips between adjacent parts representing the material your blade will remove.
Sheet number - when multiple sheets are needed, each is numbered (Sheet 1 of 3, Sheet 2 of 3, etc.).
Summary stats - total sheets, total waste percentage, estimated material cost.

Reading dimensions

Every part rectangle is labeled with its dimensions. Convention:

Length × Width (in that order). Length is usually the longer dimension.
The first number runs along the horizontal axis of the rectangle as drawn.
The second number runs along the vertical axis.

If you see "Side panel - 720 × 580", the part is 720mm wide (horizontal on the diagram) and 580mm tall (vertical on the diagram). When you cut the actual sheet, you orient the same way: long dimension across, short dimension up.

Color coding

Most optimizers assign a color per unique part name. So all "cabinet side" parts share a color, all "shelf" parts share a different color. This lets you see at a glance:

Whether you'll have many small parts or a few large ones.
Which parts pack together vs which sit isolated.
Which sheet contains which part types.

If parts have suffixes like "Side #1, Side #2," they share a color (same base name). The numbers help you track them through assembly when they have the same dimensions but different roles.

The kerf gap myth

Looking at a cutting diagram, you'll see thin gaps between parts. Those gaps represent the kerf - the strip your blade will remove. They're not actual extra material to leave during marking; they're a visualization of where the cut goes.

When you transfer the diagram to the real sheet, mark cuts as single lines. The kerf is on one side of the line - typically the waste side. The optimizer has already accounted for the kerf when sizing parts.

Cut sequence (the part most people get wrong)

A cutting diagram shows you the layout. It doesn't show you the order. Order matters. The wrong order means you trap parts in awkward positions where you can't make the next cut safely.

The standard cut sequence:

Rip the sheet down to manageable widths first. Make the long cuts that span the full sheet, separating it into 2-4 long strips. This gives you pieces small enough to maneuver on the saw without help.
Cross-cut each strip into parts. Working one strip at a time, make the perpendicular cuts that turn the strip into individual rectangles.
Cut from the largest part toward the smallest. Big parts get the first picks; small parts come from the leftover strips. This minimizes the chance of being unable to make a final cut because a part is too small to hold safely.
Make the cleanest cuts last. Your blade gets warmer and slightly less precise after 30 cuts. Save your most accuracy-critical parts (drawer fronts, doors) for the start of the session, not the end.

Reading the waste percentage

Most diagrams show overall waste as a percentage at the top or bottom. Numbers to expect:

Under 10% waste: Excellent. The optimizer found a near-perfect packing for your parts.
10-20% waste: Typical. Most projects fall here.
20-30% waste: Mediocre. Worth trying different stock sizes (see if a 5×5 sheet saves material vs a 4×8).
Over 30% waste: Bad layout. Either you have an unusual mix of part sizes or your stock sheet is wrong for the job. Re-think.

Reading multi-sheet diagrams

When the optimizer needs multiple sheets, you'll see Sheet 1 of N, Sheet 2 of N, etc. Cut sheets in order - Sheet 1 first, all parts off it, then Sheet 2. This way:

You can stop after Sheet 1 if you've made a mistake and need to reassess.
You don't mix parts from different sheets on the workbench.
The last sheet is typically the most underutilized; if you're saving offcuts for future projects, that's the one to mark and stash.

What the diagram doesn't tell you

A cutting diagram is silent on:

Grain direction. Most optimizers don't track grain. You're responsible for orienting parts so visible grain runs the right way.
Face up vs face down. Cabinet doors with a finished side need to go face-down on a table saw, face-up on a track saw. Mark the good face on the sheet before cutting.
Which face is the show face. If you have an A/C plywood and the diagram doesn't say which side is up, assume the A face is the front (show face) and orient your cuts accordingly.
Order of operations. As above - the diagram shows the destination, not the route.

Pre-cut checklist

Before you start cutting, walk through this:

Print the diagram or have it on a phone propped where you can see it.
Mark the sheet with chalk or tape: "Sheet 1," "Sheet 2," etc.
Mark the show face (A face) clearly.
Identify your first cut - usually the long rip closest to the long edge.
Set your fence to the first cut measurement plus the kerf.
Make the cut.
Set up the next cut. Repeat.

When the diagram doesn't match reality

If you measure a sheet and find it's not exactly 2440×1220 - most aren't - adjust before cutting. Re-run the optimizer with the actual sheet dimensions. Five minutes of re-planning is cheaper than realizing halfway through that your last part is 3mm short.

Bottom line

The cutting diagram is a tool, not a recipe. It tells you where parts go on the sheet but assumes you know how to translate that into a cut sequence, account for grain, and orient the show face. Get the basics right and the diagram saves you hours and dollars per project.

Open the cut list calculator to generate a diagram for your next build, or load a project template and walk through reading the resulting layout.