Packaging and Logistics

Flexible Packaging Yield: From Web Width to Cost Per Pouch

Film is bought by weight and sold as pouches, and the conversion between them is where margin quietly disappears. Most of the loss is decided when someone chooses a web width.

Converting flexible film into pouches is an exercise in fitting rectangles onto a moving web, and the arithmetic is unforgiving. You buy film by area or weight and you sell pouches by the piece, so every square centimetre that does not become a saleable pouch is margin. The largest single loss in most operations is not scrap or setup waste. It is the trim strip that runs the entire length of every roll because the web width was not chosen to suit the pouch.

The across-web calculation

Take a 620 mm web running a 145 mm pouch. You fit 4 across, using 580 mm and leaving 40 mm of trim, which is 6.5% of the web wasted on every metre run, permanently. Now consider ordering film at 600 mm instead, sized to the same 4 lanes plus a modest edge allowance: trim falls to about 3.3%. Nothing changed on the machine. The saving came from a purchase order.

• Lanes on a 620 mm web: 4 across
• Trim waste as bought: 6.5%
• Trim on a 600 mm web: 3.3%

Down-web waste behaves differently

Repeat length governs the down-web direction, and on printed film it is fixed by the print cylinder rather than by the pouch. A mismatch between repeat and pouch length produces waste on every repeat, and unlike web width it cannot be fixed by ordering differently: it requires a new cylinder. This is why the pouch dimensions, the repeat, and the web width should be decided together at artwork stage, and why changing a pouch size after cylinders are cut is far more expensive than it appears.

Trim waste is decided by a purchasing decision and paid for by production, every metre, for the life of the product.

The waste categories to separate

Report these individually or you cannot attack any of them

• Trim, which is structural and fixed by web width against pouch width.
• Repeat waste, fixed by cylinder repeat against pouch length.
• Setup and registration waste at the start of each run, which scales with the number of changeovers rather than with volume.
• Splice and roll-change waste, which scales with roll length and therefore with how the film was ordered.
• Quality rejects, the only category most operations actually track.

Getting to cost per pouch

Film cost per pouch is film cost per square metre times the pouch area, divided by one minus total waste percentage. That final division is where the waste categories above earn their separation: a five point improvement in trim moves cost per pouch by more than most negotiated film price reductions, and unlike a price negotiation it does not need the supplier's agreement.

Use the web formation yield calculator to test lane counts and trim against your own film widths. Model the web

Published 2026-08-08.