How to Cut Rebar With Less Waste: Planning Cuts From Stock Bars

Updated 5 October 2026 · العربية

Reinforcing bars are sold in fixed stock lengths (commonly 12 m, and in some markets 6 or 9 m), but the bars on your schedule are cut to many different lengths. Every stock bar is cut into pieces, and what is left over is waste. Planning the cuts well is one of the cheapest ways to save steel.

A simple example

You need many pieces of 5.1 m and 3.4 m from 12 m stock bars.

• Careless: two pieces of 5.1 m per bar = 10.2 m used, 1.8 m wasted, 15% of the bar.
• Planned: one 5.1 m piece plus two 3.4 m pieces = 11.9 m used, 0.1 m wasted, 0.8% of the bar.

The steel is the same and the order is the same, but the second plan needs fewer stock bars.

Rules that work

1. Plan by diameter. Pieces of different diameters can never share a stock bar, so make one plan per diameter.
2. Combine pieces across members. Beams, columns and slabs of the same diameter can share stock bars; do not plan each member alone.
3. Start with the long pieces, then fill the remaining space with shorter ones.
4. Choose the stock length that fits. Some lengths are available in more than one stock size: the best one gives the least waste for your list.
5. Keep useful offcuts. A 1.5 m piece is useful for short bars, spacers or stirrups.
6. Allow for laps and tolerances in the cutting length before planning, not after.

Why it is hard by hand

With a few bar marks you can plan on paper. With dozens of marks and several diameters, the number of possible combinations grows very fast, which is why this is a well-known problem called cutting stock. A program does it in seconds.

BarFlow Cutting Plan

BarFlow Cutting Plan is a small Windows program: you give it the bars (bar mark, diameter, cutting length, quantity) and the stock lengths your supplier sells, and it works out which bars to buy, how to cut every bar, the waste, and the weight and cost of the order, with a plan for each diameter and a purchase order, shown in the program and also saved in an Excel workbook. It computes the plan with an exact solver (integer programming) that looks for the least steel to buy; for very large jobs it may stop at its time limit and give a near-exact plan, so always review the result before ordering. Works offline, with an English and Arabic interface, and the first 3 runs are free. It is also available from the Microsoft Store.

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