Structural steel cut list calculator: nest tube into stock lengths
Worked Australian steel cut list example: how to nest RHS/SHS pieces into 6, 9 or 12 m stock with kerf and end trim, plus a free manual method and the offline optimiser kit.
Buying an extra length of SHS because the nest was guessed is expensive. Our cut list vs DXF guide explains when you need a saw nest versus a plasma file. This page is the calculator walkthrough with a real numbers example.
The short answer
- List every piece: section, length (mm), quantity, mark.
- Add saw kerf between cuts (measure your blade – often 1.5 to 3 mm) and end trim (often 5 to 10 mm) on each stock bar.
- Choose stock lengths your supplier actually holds (commonly 6, 7.5, 8, 9 or 12 m).
- Nest longest pieces first, fill gaps, keep offcuts above your minimum usable length (many shops use 600 mm).
- Print a buy list and a saw sheet.
Worked example – SHS 100×100×6 gate frames
Pieces: 8× 2400 mm, 8× 1200 mm, 4× 900 mm. Kerf 2.5 mm. End trim 10 mm each end of a new bar. Stock: 6.0 m (6000 mm).
Usable per new 6 m bar ≈ 6000 − 20 trim = 5980 mm, then subtract kerf between pieces.
One workable nest per bar: 2400 + 2400 + 900 = 5700 mm of metal + 2×2.5 mm kerf = 5705 mm → fits, ~275 mm scrap (below 600 mm → scrap bin).
Bars needed for the 2400s and 900s: 4 bars for eight 2400s + four 900s. The eight 1200s nest as 4×1200 per bar with kerfs → 2 more bars. Buy list: 6 bars of 6.0 m SHS 100×100×6. Weight check: use our kg/m formulas before you order.
Manual calculator steps
- Sort pieces longest to shortest.
- Open a new stock bar, subtract end trim once.
- Place the longest piece that fits; subtract length + kerf.
- Repeat until nothing else fits above your scrap threshold.
- Start the next bar. Prefer using rack offcuts before new bars.
Doing this by hand is fine for ten pieces. For weekly nests, the offline optimiser below does the packing for you.
Related: metric plasma files for base plates and gussets are in the base plate DXF guide.
Quick answers
What kerf should I type into a cut list calculator?
Measure your own blade. Guessing is how every piece comes up short.
Should I nest into 12 m every time?
Only if you can handle and transport it. Many shops prefer 6 or 9 m for yard space even if waste is slightly higher.
Do offcuts go back into the nest?
Yes if they are above your minimum usable length and the same section. Track them on a rack list.
Is a cut list the same as a DXF?
No. A cut list is for the saw. A DXF is for CNC plate cutting.
Sources
- Australian Steel Institute
- Andwat – Steel weight per metre formulas
- Andwat – Cut lists vs DXF plasma files
Related guides
- Steel cut lists vs DXF plasma files
- Steel weight per metre formulas
- Plasma DXF base plate files
- Fabrication ITP guide
General information only, summarised from the official sources above as at the review date. It isn't legal, WHS or engineering advice. Rules change and your situation may differ, so check the source or ask a professional.