Steel Nesting Calculator

Nest a steel cutting list into the fewest bars. 1. Import (or type in) the material you need to cut, with mark numbers. 2. Check the mill lengths each of those materials can be ordered in. 3. List any bars or offcuts you already have on the rack for them. Then press NEST: you get a bar-by-bar cutting plan, the offcuts left over, and an order list of standard lengths with total weight. Everything runs in your browser and is saved locally – nothing is uploaded.

Lengths are entered in millimetres. The lengths to order from are pre-loaded per material size from the supplier guide and fully editable to match what your supplier stocks.

Or add items by hand:

One row for each material in the cutting list. Lengths in metres, comma separated (maximum 20 m). The nest only buys from a material’s own row: delete lengths your supplier doesn’t stock in that size; add any they do.

Import or add the cutting list above first – each material in it will appear here with the lengths it can be ordered in.

Rows are pre-filled per size from the Surdex Steel reference guide: hot-rolled sections in the usual mill lengths; flats, rounds and squares 6 m; 20/25 SHS 6.5 m only; 30–65 SHS and small RHS 8 m only; larger SHS/RHS 8 and 12 m; 89 SHS 8, 9 and 12 m; CHS pipe 6.5 m, 9 and 12 m from 168 OD. An edited row applies to that material only; Reset defaults restores the guide data for every row.

Bars and offcuts already on your rack for the materials in the cutting list. The nest always uses these before buying new material.

Kerf is the material lost to each saw cut. End trim is removed from both ends of every bar (e.g. to square mill ends). Leftovers shorter than the minimum usable offcut are counted as scrap.

Methods: 2.1 packs each bar tightly one at a time. 2.2 re-runs 2.1 many times with shuffled orders and repairs the worst bars. 2.3 optimises the whole mix of cutting patterns at once (column generation) and reports how close to the mathematical minimum it got. 2.4 searches for the provably optimal nest – can take several seconds on big jobs. All methods use rack stock first and never do worse than 2.1.

The best result (least new material) is shown in bold and displayed below. Optimality compares against the mathematical lower bound where the method computes one.

Every method starts the same way. Pieces are sorted longest first and each is placed into the stock-on-hand bar it fills tightest (best-fit), so rack offcuts are used up before new material is bought. Saw kerf is allowed for between every cut, and end trim comes off both ends of every bar.

What is left is nested onto new bars from the lengths to order, by the method chosen under Cutting settings:

• 2.1 Standard packs one bar at a time as tightly as it can, trying each available length and buying the one that leaves the least waste. Fast, and the base every other method must match or beat.
• 2.2 Multi-start + repair re-runs 2.1 many times with the pieces in shuffled orders and repairs the worst bars, keeping the best result found.
• 2.3 Column generation (the default) optimises the whole mix of cutting patterns at once and computes the mathematical lower bound on the material needed. The Optimality tile shows how close it got: Matches bound means no nest can use less.
• 2.4 Exact search looks for the provably optimal nest. Proven optimal means it finished the search; Best found (capped) means it ran out of time and shows the best it found. It can take several seconds on a big job.

2.1 and 2.2 are heuristics and make no optimality claim. COMPARE METHODS runs all four on the same list and shows the results side by side. Pair the nest with the free Steel Quote take-off calculator to price the material it tells you to order.