Cutting waste in rebar fabrication: what percentage is normal

Updated: 2026-08-04 · ISKRIT

A waste percentage on a cutting plan and a waste allowance in a contract are two different quantities, and quoting one against the other is how arguments about steel start.

Two distinct numbers

Cutting offcut is the end piece too short to be used for anything in the current schedule. It is a property of the schedule and the stock length, and a good plan moves it between two and five percent on ordinary reinforcement work.

Unavoidable loss is everything else: the scrap from straightening coil, the damaged ends, the bars rejected at inspection, the pieces cut wrong. It is a property of the shop, not of the plan, and it is budgeted at around one percent.

The two are added, not compared. A supplier reporting three percent waste who means offcut only, faced with a client who reads it as everything, is short by the shop loss.

What drives offcut up

Piece lengths that are just over half the stock length are the worst case: two do not fit, one leaves nearly half a bar. A schedule dominated by such lengths cannot be optimised out of a high waste figure, and the fix is upstream, in the detailing, not in the saw shop.

Diameter fragmentation is the other driver. Each diameter and each steel grade is a separate cutting problem, because pieces of different diameters cannot share a bar. Ten diameters with small quantities each will waste far more than the same tonnage in three diameters.

Reading a quoted figure

Ask three questions of any waste percentage: is it offcut only or total loss, is it computed on length or on mass, and does it count returned offcuts as waste or as stock. Length and mass differ whenever several diameters are involved, since a percent of length in 8 mm bar is a much smaller mass than a percent in 32 mm. Offcuts returned to the rack are not waste at all unless the project ends before they are used.

The cutting plan tool reports offcut separately from reusable remainder, in both length and mass, so the figure can be quoted without ambiguity.