Calculating plywood yield for kitchen cabinets
Worked example: calculating plywood yield for a kitchen cabinet run in 18 mm birch ply, why 85% is a good target, and how grain and backs change the count.
A kitchen cabinet run is the clearest place to see what yield actually costs, because the parts are simple rectangles and the sheet count directly sets your material budget. Do the arithmetic before you order, and you'll know whether that quote from the supplier is generous or thin. This walks through a real run — base and wall cabinets — from raw part list to sheets ordered.
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The job: base and wall cabinet run
Take a kitchen with 5 base cabinets and 4 wall cabinets, all boxes built from 18 mm birch ply with 6 mm ply backs, no face frames, edge-banded fronts. Each carcass needs two sides, a bottom, a top rail or top panel, and a back. Doors and drawer fronts are ordered separately in a different material and aren't part of this sheet count.
| Part | Size (mm) | Qty | Notes |
|---|---|---|---|
| Base cabinet side | 720 x 560 | 10 | Grain must run vertical |
| Base cabinet bottom | 560 x 500 | 5 | Grain direction not critical |
| Base cabinet top rail | 560 x 100 | 10 | Front and rear rail per box |
| Wall cabinet side | 700 x 300 | 8 | Grain vertical |
| Wall cabinet top/bottom | 700 x 280 | 8 | Grain not critical |
That's 41 structural parts in 18 mm ply, totalling 6.94 m² of finished part area. Backs are a separate material — 6 mm ply — covered later.
Theoretical yield: area math only
A sheet of 2440 x 1220 mm has 2.977 m² of usable area. Nine parts' worth of area (6.94 m² total) divided by sheet area gives a theoretical minimum of 2.33 sheets — meaning if every scrap could be reused with zero kerf and perfect tessellation, you'd need just over two and a third sheets. That number is useful only as a ceiling; no real cutting plan hits it.
Why 85% is a realistic target, not 100%
Real yield loses ground to three things: kerf width removed at every cut line, grain-direction constraints that stop parts from rotating to fill gaps, and irregular leftover shapes too small to reuse. A well-nested, grain-respecting layout on straight rectangular cabinet parts typically lands around 82-88% yield. Anything above 90% on a real cabinet job usually means the parts are unusually uniform in size, or someone mixed grain direction where it wasn't supposed to be mixed — check that before celebrating.
| Yield achieved | Effective usable area per sheet | Sheets needed |
|---|---|---|
| 100% (theoretical) | 2.98 m² | 2.33 |
| 85% (realistic target) | 2.53 m² | 2.74 → 3 sheets |
| 70% (poor layout, mixed grain) | 2.08 m² | 3.34 → 4 sheets |
The gap between a realistic 85% layout and a careless 70% layout is a full extra sheet — about €58 at typical birch ply pricing, on a job this size. On a whole-house kitchen with 30+ cabinets, that gap becomes 4-5 sheets, easily €250-300.
Grain-locked parts change the nesting, not just the math
Cabinet sides are visible in most kitchens, so their grain runs vertically to match the door grain above and below — you cannot rotate them 90° to fill a leftover strip even if the strip is the right size. Bottoms, top rails, and anything hidden inside the box can usually run either direction, which gives your nesting software room to tuck them into odd corners the visible parts can't use. When you build your part list, mark grain direction explicitly for every part — a grain direction guide is worth the ten minutes if you're not already doing this by habit, because getting it wrong after cutting means remaking a visible part.
Backs from 6 mm ply: a separate sheet count
Cabinet backs don't need 18 mm strength; 6 mm ply, sometimes even 4 mm hardboard, is standard and lets a single sheet cover far more backs than the same sheet would in 18 mm. Nine cabinets need backs sized roughly to the carcass opening — call it 4.6 m² of 6 mm material. One 2440 x 1220 mm sheet of 6 mm ply at 85% yield gives you 2.53 m² usable, so this run needs two sheets of 6 mm ply, entirely separate from the 18 mm order. Forgetting to budget backs as a second material line is one of the most common quoting mistakes on cabinet jobs — they're easy to overlook because they're invisible in the finished cabinet.
Cost per cabinet, worked through
Three sheets of 18 mm birch ply at roughly €58 each plus two sheets of 6 mm ply at roughly €32 each comes to €238 in sheet material for 9 carcasses, or about €26.40 per cabinet in structural ply — before edge banding, hardware, doors, and finish. That per-cabinet figure is what you compare against a supplier's flat-rate carcass pricing to see whether building in-house actually saves money once labour is factored in.
Building the cut list without guesswork
Enter every part with its exact size, quantity, grain flag, and your measured kerf into a cut list optimizer rather than eyeballing a sheet diagram — grain-locked rectangles are exactly the case where manual nesting underperforms software by 5-10 points of yield, because a person tends to place parts in list order rather than solving the packing problem. Load the example cabinet project to see a similar carcass run pre-built if you want a starting template.
Banking offcuts for the next run
A three-sheet order for this job rarely leaves zero offcut, and treating every leftover strip as scrap is a habit worth breaking. After the 41-part nest, a typical 85% yield layout leaves one or two strips in the 250-400 mm width range per sheet — often enough for a full wall cabinet top rail or a drawer bottom on the next job. Keep a labelled offcut rack sorted by material and thickness, and log each piece's size before it goes on the shelf. Shops that do this consistently report shaving half a sheet or more off small repair and add-on jobs, because the part they need is already sitting there instead of triggering a fresh sheet purchase.
Sanity-checking a supplier's flat-rate carcass quote
When a cabinet supplier quotes a flat rate per carcass instead of itemising material, run your own numbers first so you know what you're comparing against. Using the €238 sheet total from this run plus a rough labour estimate — call it 3 hours per box at a loaded shop rate of €45/hour for cutting, edge banding, and assembly — gives an in-house cost near €41 per cabinet before doors. If the supplier's flat rate sits meaningfully above that, ask what grade of ply and what edge-banding spec they're using; a quote that looks expensive on the surface sometimes reflects thicker backs or better core material than your own spec, and a quote that looks cheap sometimes means melamine-faced particleboard standing in for birch ply.
Common takeoff mistakes that inflate sheet counts
- Forgetting stretcher rails or nailers — hidden structural strips at the top and bottom of a carcass are easy to leave off a first-pass part list and then get added as a rushed afterthought that doesn't nest well.
- Counting a mirrored pair as one part — left and right cabinet ends are usually identical rectangles, but if your drawing package treats them as separate named parts you can end up double-counting or under-counting quantity.
- Ignoring adjustable shelf holes as a layout constraint — shelf-pin drilling doesn't change sheet count, but doing it before final trimming can shift a part's usable orientation if you drilled off-centre.
- Applying one universal kerf to every saw in the shop — if the same job gets ripped on a table saw and crosscut on a track saw, use each machine's measured kerf rather than a single average value.
Bottom line
A kitchen cabinet run's real yield sits around 85%, not the 100% area math suggests, and grain-locked sides plus a separate thin-ply back order are the two things that most often blow a rough estimate. Work the numbers per material thickness, mark grain explicitly, and price backs as their own sheet count.
Next steps. Build this exact part list in the free cut list optimizer and compare its sheet count against your own manual estimate, then check cabinet carcass cut lists for more carcass-specific layout rules.