How to lay out plywood cuts to minimize waste

Start with a cut list and a drawn sheet

A cutting diagram starts as a list: every part with its width, length, quantity and a name you will recognize at the saw. Kreg's guide to breaking down plywood suggests drawing the sheet outline in pen and the parts in pencil, so you can erase and rearrange until the layout works, then marking each cut part with chalk, which is easy to see and wipes off with a damp rag.

Draw the sheet you will actually cut. Wikipedia's plywood article gives 4 by 8 feet as the common imperial size and 1200 by 2400 mm as a common metric size, so measure the sheet in front of you rather than assuming.

Then check the edges. Woodsmith notes that not all plywood comes from the manufacturer square, and Bent's Woodworking points out that sheet edges take abuse from forklifts, nylon straps and weather on the way to your shop. Leave room in the layout for a trim cut along any edge you plan to use as a reference.

Use only cuts a saw can make

Table saws, panel saws and track saws cut in straight lines from one edge of a piece to the other. Wikipedia's article on guillotine cutting defines that kind of cut as a straight line running from one edge of a rectangle to the opposite edge, and lists cutting wood sheets for furniture among its uses. A layout that nests parts like puzzle pieces may use more of the sheet on paper, but it asks for cuts that stop partway across the panel, which is not how these saws work.

Plan the order as a series of those full cuts. The first cuts break the sheet into strips, and each strip is then cut into parts. Sources differ on which direction to start. Kreg's example begins with crosscuts across the sheet and then rips the pieces to width, while Bent's Woodworking rips first and crosscuts second because that makes the sheet easier to manage on a table saw. Pick the order that keeps each piece at a size your saw and your support can control.

Every cut also removes a strip of material. TableSawGuide's advice is to add the blade kerf between each pair of parts when you plan. On a 48 inch wide sheet with a 1/8 inch kerf, three 16 inch strips do not fit: after two strips and two cuts, 15 3/4 inches are left.

Arrange the parts for yield

Place the largest parts first. SmartCutList's guide makes the point that big pieces constrain the layout the most, while small ones can fill the gaps they leave behind. Kreg adds that lining up parts with the same or similar dimensions helps you cut more effectively, because one fence setting or one rip can then produce several parts.

Respect grain where it shows. According to Kreg, the grain runs lengthwise on a plywood sheet, so cabinet sides, doors and drawer fronts that should match need to keep that orientation. For painted projects Kreg notes the grain will not show, which frees those parts to turn 90 degrees wherever they fit better.

Measure yield honestly. Yield is the area of the finished parts divided by the area of the sheets you used, and offcuts too small to reuse count as waste. Comparing two layouts by sheet count and yield tells you which one really saves material.

Do not expect a perfect answer. Wikipedia notes that once there are two or more part sizes, the optimization problems in guillotine cutting are NP-hard, which means there is no known fast method that always finds the best layout. Hand layouts and software both rely on rules of thumb and trial, so try more than one arrangement before you cut.

Keep offcuts in play

Offcuts are material you already paid for. After each job, measure the pieces worth keeping, write the dimensions on them, and check that pile before you open a new sheet for the next project.

Store them flat and keep the list current. A pile you cannot see into gets ignored, and a list that still shows a piece you already used sends you to the rack for nothing.

SawNest, a cut list app for sheet goods, follows the same rules: it produces only guillotine layouts, subtracts the kerf you set from every cut, lets you lock grain on individual parts, and keeps an offcut inventory that the next project tries before it opens a fresh sheet. An offcut leaves that inventory only when you confirm a layout.

Common layout mistakes

Forgetting the kerf. Parts come out short, or the last one on a strip does not fit at all. Add one kerf for every cut in the layout.

Trusting the factory edge. If the sheet is out of square, every part referenced from that edge inherits the error. Trim a clean reference edge first.

Rotating show parts. Turning a visible part sideways to fit a gap can save material and spoil a matched set of doors. Decide which parts need grain direction before you start moving pieces around.

Cutting to final size on the first pass. Bent's Woodworking describes breaking sheets down slightly wide with a track saw and bringing parts to final dimension on the table saw. If your first cuts are made with a circular or track saw, leave that allowance in the layout, and check every dimension against the actual sheet before you cut, because a cutting diagram is a plan, not a measurement.

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