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Rebar Stock Cutting Calculator

Segments, offcut, purchase quantity and utilisation.

Quick answer

With the default inputs: Required length 3.5 · Pieces required 500 pcs · Stock length 12 m etc.Stock bars to buy 167 bars

Edit the inputs below to recalculate.
Length LΦ d
Stock is 9 m or 12 m; segments per bar is (stock − kerf) ÷ cut length rounded down. Only the leftover is real waste.

Inputs

pcs

Result

Stock bars to buy
167bars
Segments per bar3strips
Offcut per bar1.50m
Utilisation87.3%
Total stock length2004m
Stock weight4.95t
Finished weight4.32t
Waste weight0.63t

Utilisation = finished length ÷ purchased stock length. Offcuts that can serve other locations (stools, ties, short stirrups) lift the real figure, so pool offcuts by size before ordering. Stock choice matters: 3.5 m pieces on 12 m stock give 3 per bar with 1.5 m left; on 9 m stock only 2 with 2 m left, which is worse. For large volumes, run combined patterns on one bar.

Formula

Segments = floor((stock + kerf) ÷ (need + kerf))
Offcut = stock − n×need − (n−1)×kerf
Bars to buy = ceil(pieces ÷ segments)
Utilisation = finished length ÷ (bars × stock)
3.5 m pieces, 500 of them, on 12 m stock: 3 per bar with 1.5 m left, 87.3% utilisation, 167 bars. On 9 m stock: 2 per bar with 2 m left, 250 bars, and utilisation drops to 77.8%.

How to work it out

  1. Pieces per stock length: k = ⌊stock length ÷ required length⌋.
  2. Stock bars required = ⌈pieces required ÷ k⌉.
  3. Utilisation = (k × required length) ÷ stock length × 100%; the remainder is offcut.
  4. Total weight = stock bars × stock length × 0.00617 × d².
  5. Allow for cut loss: 3-5 mm per abrasive cut and 5-8 mm per flame cut, which adds up over thousands of pieces.

Where it goes wrong

Material and cost

Steel runs 4,200-5,000 per tonne, so every 5% cut from the offcut rate is 5% off the material bill. On a 1,000 t project that is 210,000-250,000. Centralised cutting optimisation is the most direct saving in bar fabrication.

On site

Basis

FAQ

Why is longer stock more efficient?
Each bar carries a fixed offcut. Cutting 3.5 m on 12 m yields 3 pieces and 12.5% waste; on 9 m only 2 pieces and 22%. Longer stock means more segments and a smaller waste fraction. But it turns bad when the piece approaches half the stock: 6.5 m on 12 m gives one piece and 46% waste - lap it or change the stock.
Can offcuts be counted as usable material?
Only if some component needs that length - 1.5 m pieces suit stools, ties and short stirrups. Otherwise they are scrap at roughly a quarter of the bar price. List offcuts first, see what can absorb them, then choose stock length. That is where bar-bending yards actually save money.
Why count kerf loss?
Every cut removes 3-10 mm (more with an abrasive saw). Three pieces from one bar mean 2 cuts, or 4 if both ends are trimmed - 20-40 mm of loss. Trivial per bar, it becomes 20-40 m over a thousand. For precision work such as coupler splices with square-cut ends, it must be included.

Cite this page

Use this format in reports, method statements or coursework. The link is permanent.

Building Calculator. Rebar Stock Cutting Calculator. 2026-10-25. https://jianzhujisuan.com/en/rebar-stock-cut

Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.