Nesting is arranging parts on a sheet so that as many as possible fit. Whatever is not a part, the skeleton between them and the cut-outs inside them, is material you paid for and usually scrap. Sheet utilisation is the share of the sheet that leaves as product, and it decides how much material each part should carry on its price.
Key points
- Utilisation measured by bounding rectangle flatters you; measured by net part area it shows the real waste.
- The skeleton and internal cut-outs are paid for whether or not you charge for them.
- Charging by net area, by bounding box plus waste, or by sheet share gives very different material prices.
- Small orders on special material may have to carry the whole sheet unless remnants are reused.
- Mixed nesting, rotation and filling cut-outs with small parts raise utilisation.
What nesting is
On a laser cutter, waterjet, plasma cutter, punch press or router, parts are cut from standard sheets. The nesting step lays them out: rotating them, interlocking them, mixing different parts on one sheet, and leaving the minimum gap between them. The gap has to allow for the kerf, the width the beam or jet removes, plus enough material between parts to stop heat or the cutting force distorting them.
Nesting software does this automatically, but its result depends on the parts. Rectangles nest almost perfectly. Discs and L-shapes leave gaps that no arrangement can remove. Parts with a large hole in the middle waste the hole, unless something smaller can be cut from it.
Two ways to measure utilisation
Sheet utilisation is the share of the sheet that ends up as parts. It matters whether you measure parts by their outline or by their actual material.
| Measure | What it counts | What it tells you |
|---|---|---|
| Bounding-box utilisation | Each part’s enclosing rectangle | How well the nest packs outlines; ignores cut-outs |
| Net utilisation | The real area of each part, holes removed | How much of the material you bought is sold |
| Sheet share | Cost of the sheets used ÷ parts cut | The material cost each part really carries |
A nest can look excellent by outlines and still waste a lot of material inside the parts. When you price material, net utilisation and sheet share are the numbers that matter.
Worked example: one part, three material prices
The figures are illustrative assumptions, not market prices. A shop cuts a bracket from 3 mm mild steel on a 3000 × 1500 mm sheet. The bracket’s outline is a 250 × 180 mm rectangle, and after its cut-outs its net area is 0.036 m². The nest keeps a 10 mm margin at the sheet edge and a 10 mm gap between parts.
Worked example: parts per sheet and material per part (illustrative prices)
| Line | Calculation | Result |
|---|---|---|
| Sheet area | 3.0 m × 1.5 m | 4.5 m² |
| Sheet weight | 4.5 m² × 23.55 kg/m² (3 mm × 7.85 kg/dm³) | 105.98 kg |
| Sheet cost | 105.98 kg × €1.20/kg | €127.17 |
| Usable area | (3000 − 20) × (1500 − 20) mm | 2980 × 1480 mm |
| Orientation A: 250 mm along the length | 11 × 250 + 10 × 10 = 2850 mm; 7 × 180 + 6 × 10 = 1320 mm | 11 × 7 = 77 parts |
| Orientation B: 180 mm along the length | 15 × 180 + 14 × 10 = 2840 mm; 5 × 250 + 4 × 10 = 1290 mm | 15 × 5 = 75 parts |
| Bounding-box utilisation (A) | 77 × 0.045 m² = 3.465 m² ÷ 4.5 m² | 77.0% |
| Net utilisation (A) | 77 × 0.036 m² = 2.772 m² ÷ 4.5 m² | 61.6% |
Material cost per bracket, three ways (steel at €1.20/kg = €28.26/m²)
| Charging method | Calculation | Per part |
|---|---|---|
| Net area only | 0.036 m² × €28.26/m² | €1.02 |
| Bounding box | 0.045 m² × €28.26/m² | €1.27 |
| Share of the sheet | €127.17 ÷ 77 | €1.65 |
| Whole sheet, order of 20, no remnant reuse | €127.17 ÷ 20 | €6.36 |
The same bracket carries anything from €1.02 to €6.36 of material depending on how you charge. Charging net area only means the shop absorbs 38.4 percent of every sheet as an unpriced loss. Charging the sheet share recovers the whole sheet when it is full. And a twenty-part order on a sheet nobody else will use carries the whole sheet unless the shop can sell or reuse the remainder, which is one reason cutting shops set a minimum order value.
The leftover strips in this nest are 130 mm and 160 mm wide, too narrow for another bracket in either orientation. A smaller part from another job could fill them, which is the case for mixed nesting.
Three ways to charge material
| Method | How it works | Fair when | Risk |
|---|---|---|---|
| Net area × waste factor | Part area divided by an expected utilisation | You fill sheets with mixed jobs and know your typical utilisation | The factor drifts away from reality if not checked |
| Bounding box plus waste | Enclosing rectangle plus a margin | Parts are roughly rectangular | Overcharges parts that nest inside each other; undercharges odd shapes |
| Share of the sheet | Cost of the sheets used for the job ÷ parts | Dedicated sheets per job, common or special material | Small orders look expensive; needs a remnant policy |
| Customer-supplied | Customer provides the sheet | Customer has the material | Handling and liability for scrap must be agreed |
Many shops use the first method for common materials, where the remainder of the sheet goes into the next job, and charge the full sheet or a minimum sheet fraction for special-order materials, where it would not. Whatever you choose, it should be one setting you can check against real nests, not a guess in each quote.
How to raise utilisation
| Technique | What it does |
|---|---|
| Allow rotation | Lets the nest turn parts 90° or freely to fit gaps |
| Mixed nesting | Fills gaps with parts from other jobs in the same material and thickness |
| Part-in-part | Nests small parts inside the cut-outs of large ones |
| Common-line cutting | Shares one cut between two straight-edged neighbours, saving cut length and material |
| Remnant management | Stores usable offcuts and nests later small jobs on them |
| Quantity advice | Tells buyers which quantities fill a sheet cleanly |
Some of these are constrained by the part. Grain direction on brushed stainless, or rolling direction for bending, may forbid rotation. Common-line cutting needs straight shared edges. Small parts in cut-outs need micro-joints so they do not tip into the slats.
The same idea in 3D printing
Powder-bed printing has the same problem in three dimensions. In SLS and MJF the build volume is the sheet, and how tightly parts pack, the packing density, decides each part’s share of the build’s machine time and powder. Our article on SLS pricing and nesting covers it, and the logic carries over directly: charge each part for the share of the resource it really consumed.
Putting it into a quote
A sheet part’s material line should come from a stated method and a utilisation figure you have measured, not from net area alone. The laser cutting cost guide shows where this line sits next to cutting time and pierces, the sheet metal fabrication cost guide adds bending and finishing, and the laser cutting cost calculator lets you try different utilisation figures. Quotometry prices laser, waterjet and plasma cutting today, with the sheet charged by bounding box plus a margin, net area plus waste, or a typical utilisation figure; it does not nest parts from different lines on one sheet.
Questions people ask
What is nesting in laser and sheet cutting?
Nesting is arranging the parts to be cut on a sheet so that as many as possible fit, with the minimum gap between them that the process allows. Nesting software rotates and interlocks parts, mixes different parts on one sheet and plans the cut order. Good nesting reduces the material each part consumes and so the price.
What is a good sheet utilisation?
It depends heavily on the part shapes. Rectangular parts can nest very tightly, while round or L-shaped parts leave unavoidable gaps, and parts with large internal cut-outs waste the cut-out unless smaller parts are nested inside it. Rather than chase a general figure, track your own utilisation by material and part type and price from that.
Should I charge customers for the whole sheet?
Only when the rest of the sheet cannot be used. If you keep and reuse remnants or fill sheets with other jobs, charging the whole sheet to one small order overcharges that customer. If the material is special-order and the remnant will sit unused, charging the whole sheet, or a large share of it, is fair and should be stated on the quote.
Does nesting matter for 3D printing too?
Yes, for powder-bed processes such as SLS and MJF. There the build volume plays the role of the sheet, and parts are packed in three dimensions. The share of the build a part occupies, and the packing density achieved, set its share of the machine time and powder cost, in the same way that sheet utilisation sets a cut part's material cost.
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