Sheet utilization in nesting: what it is and how it affects price
Sheet utilization is the share of sheet area occupied by nested parts. It is a packing score, not a profit guarantee. This guide defines the idea, explains why 100% never happens in real laser work, and shows how AllTerra Calculator reports utilisation from the nest.
Definition and formula
In plain language, utilisation asks: of the sheet metal you committed to this job, how much area is covered by parts? Higher utilisation usually means less remnant for the same part set — so material cost per part can fall — but only if the sheet count does not rise for other reasons.
A common one-sheet definition is: utilisation % = (area of parts on the sheet ÷ sheet area) × 100. Multi-sheet jobs use the same idea over total sheet area used. Exact accounting can use union of part footprints so overlaps are not double-counted. Always read the number as “share of sheet area occupied,” not “share of money saved.”
AllTerra recalculates nesting utilisation from placements: for each sheet it takes a capped placed area, sums across sheets, divides by (sheet width × sheet height × sheet count), and caps at 100%. That is an area packing metric from the nest result.
Why 100% utilisation is impossible
Even a perfect rectangle tiling leaves process clearances. Laser cutting needs space for kerf, heat, and handling. Shops also keep an edge margin so parts are not cut on the sheet frame clamps.
- Edge margin — keep-out from the sheet border (AllTerra orders expose edge margin in millimetres).
- Part spacing — gap between neighbouring contours (AllTerra API default 2 mm, allowed range 0–20 mm; engine rejects a true zero gap).
- True-shape parts — brackets and triangles leave pockets that rectangles cannot fill without breaking spacing rules.
- Remnants — usable leftover strips may still be counted as unused sheet area for this order’s utilisation.
So “good” utilisation is shop- and geometry-specific. A decorative nest of many small washers can look dense and still leave kerf corridors. A few large panels can show modest utilisation with little practical remnant you can reuse.
How utilisation affects price
Material cost is driven by how many sheets the nest consumes and what those sheets cost in your catalogue — not by the utilisation percentage alone. Two nests with the same utilisation can differ in sheet count if quantities or sheet formats differ.
Utilisation still helps estimators judge waste. If packing is poor, you may try rotation policy, shared cut, or a different sheet format before locking a quote. Cut length and pierces also change with packing and drive machine time; utilisation is only one of several result metrics.
Do not invent a worldwide average utilisation for marketing. Shops differ. Use the number from your nest on your sheet size.
Synthetic demo numbers (public home animation)
The public demo on nestingcalculator.com uses an open synthetic set — not a customer file. Verified published metrics:
| Metric | Value (synthetic) |
|---|---|
| Sheet size | 480 × 300 mm |
| Parts placed | 12 |
| Holes in the set | 22 |
| Part area (sum) | 36 086.64 mm² on a 144 000 mm² sheet |
| Utilisation (same sheet basis) | 25.06% |
| Gap / edge in the demo | 2 mm / 2 mm |
These figures describe only that public demo. They are not a shop average and not a promise for your parts.
In AllTerra Calculator
After nesting, the result shows order utilisation and can show per-sheet best/worst utilisation in the UI. History stores utilisation with the job. The PDF quote can include nesting diagrams captioned with sheet number, part count, and utilisation.
Unload modes on the order form include a “Maximum utilisation” style option among other unload strategies (lamellae, micro-joints). That controls how small parts are handled for unloading economics — it is not a magic override that forces 100% packing.
Quick sheet-fit hints before a full nest can show an estimated utilisation from cutting-plan arithmetic; the live hint text warns that real nesting usually places a few percent fewer parts than that pre-nest estimate.
Practical reading for estimators
Compare nests on the same sheet format and quantity. A three-point rise in utilisation that adds a sheet is not a win. Watch sheet count and cut length together.
Remnant strips that look large on the plot may still be below your reuse minimum. Utilisation does not mark remnant as sellable stock — your warehouse rules do.
For the product path from nest metrics into money, read the nesting engine page and how pricing works. To try your own DXF, sign in at calc.1cterra.ru.
When you change only gap or edge margin, utilisation and sheet count can move in opposite directions from cut length. Record all four metrics on the quote worksheet so a denser-looking plot is not mistaken for a cheaper job.
Mixed material or mixed thickness orders are nested in separate sheet groups in the live service. Utilisation on one group does not describe another. Quote each group’s packing on its own sheet format and catalogue price.
If a customer asks for a utilisation guarantee, answer with the nest you priced — sheets, gap, rotation lock, and shared-cut setting — not with a generic industry percentage. The calculator reports what that nest achieved; it does not certify a shop-wide average.
Training tip: take the public 480×300 mm demo numbers above, then re-nest the same synthetic idea on a larger production sheet in your account. You will see utilisation rise while absolute remnant area may still be large enough to reuse. That teaches why percentage and leftover metres answer different questions.