4 min read
Stretch film is bought by the kilo and consumed by the pallet, and almost nobody knows their cost per pallet. That gap is worth money to whoever is selling you film: a lower price per kilo on thicker film with less pre-stretch wins the order and makes your wrapping more expensive.
A typical European pallet — 1200 × 800 mm, 1500 mm of goods, wrapped up and down with two turns at the base — takes 40 metres of film on the load. What that costs depends almost entirely on one setting.
The load
From the top of the pallet to the top of the goods.
The film
In microns. If your supplier quotes gauge, divide by 4 for sacks — but for film, one gauge is 0.254 µm.
What the wrapper is set to. Hand wrapping achieves 0–30%.
The wrap cycle
Turns held at the bottom to tie the load to the pallet.
This calculator works out the answer in your browser, so it needs JavaScript switched on. If you would rather not, send us the figures and we will run it for you — the answer comes back the same day.
Film weight is calculated from the wrap geometry at a polyethylene density of 0.92 g/cm³. It assumes the pre-stretch you set is actually being achieved — worth checking, because a wrapper set to 250% that is slipping delivers nearer 150%, and the film bill is the first place it shows.
Want this as a PDF? The answer above is yours either way. The PDF is the working written out — the figures you entered, the result, and the assumptions behind it — for a colleague or a purchase requisition.
The arithmetic, so you can check it
Four steps, and every one is checkable against your own wrapper:
- Turns. 500 mm film at 20% overlap climbs 400 mm per turn, so 1500 mm takes four turns going up. Up and down is eight, plus two reinforcement turns at the base — ten turns.
- Film on the pallet. Ten turns around a 4.0 m perimeter is 40 metres.
- Film off the roll. This is where pre-stretch acts. At 150% pre-stretch one metre from the roll becomes two and a half on the pallet, so 40 metres applied costs you 16 metres of roll.
- Weight. 16 m × 500 mm × 23 µm of polyethylene at 0.92 g/cm³ is 169 grams. At €2.20 a kilo, €0.372 a pallet.
Pre-stretch is the whole argument
Raise that wrapper from 150% to 250% and nothing about the wrap changes. Same ten turns, same 40 metres on the load, same containment. But one metre from the roll now becomes three and a half, so the same pallet draws 11.4 metres instead of 16 — 121 grams instead of 169, and €0.266 instead of €0.372.
| At 150% | At 250% | |
|---|---|---|
| Film drawn from the roll | 16.0 m | 11.4 m |
| Film per pallet | 169 g | 121 g |
| Cost per pallet | €0.372 | €0.266 |
| Pallets from a 15 kg roll | 88 | 124 |
For a plant wrapping 60 pallets a shift — 13,800 pallets a year — that is €5,139 against €3,671. A saving of €1,468 a year and two thirds of a tonne of polyethylene, for a setting change on equipment you already own.
This is why the calculator leads with that figure. It is usually the largest single saving available in a packaging operation, and it costs nothing.
The catch worth knowing about
The calculation assumes the pre-stretch you set is the pre-stretch you get. A carriage set to 250% whose rollers are worn or slipping delivers nearer 150%, and there is no alarm for it — the pallets still come out wrapped.
The film bill is where it shows. If your consumption per pallet has drifted up without the loads changing, measure it: mark a metre of film on the roll, run a cycle, and see how far the mark travels. It is a five-minute check that has found a four-figure annual leak more than once.
Why a cheaper film can cost more
Take the same pallet at 250% pre-stretch and two quotations:
| 23 µm at €2.20/kg | 30 µm at €1.95/kg | |
|---|---|---|
| Price per kilo | — | 11% cheaper |
| Film per pallet | 121 g | 158 g |
| Cost per pallet | €0.266 | €0.308 |
| Cost per year, 13,800 pallets | €3,671 | €4,244 |
The cheaper film costs 16% more per pallet and €573 a year more, because you are buying 30% more polyethylene to do the same job. The price per kilo was the wrong question.
Thicker film is sometimes the right answer — sharp-edged loads, long sea freight, anything that has to survive being handled four times — but it should be chosen for containment, not because it looked cheaper on a price list.
Hand or machine
The threshold is about 30 pallets per shift.
Below it, a wrapping machine is hard to justify on film alone: the machine, its service, its downtime and the operator waiting for it cost more than the film they save.
Above it, hand wrapping gets expensive fast. Hand film is applied with almost no pre-stretch — 0 to 30% is what a person achieves — so the same pallet that costs €0.266 by machine at 250% costs €0.716 by hand at 30%, and €0.931 at no stretch at all. A plant hand-wrapping 60 pallets a shift is spending €9,883 a year on film where €3,671 would do. A semi-automatic wrapper pays for itself on the film alone, usually inside a year, before anyone counts the labour.
Microns, not gauge
If your supplier quotes film in gauge, one gauge is 0.254 microns — so 80 gauge is 20 µm and 90 gauge is 23 µm.
It is the same conversion the sack trade uses, where it gets rounded to four gauge per micron. What differs between the two products is not the scale but what a number means on it: 23 µm is a normal machine film and a very light refuse sack. Quote a film thickness against a sack specification and the number converts perfectly while describing the wrong product. The micron and gauge converter shows both readings of the same figure.
What we quote
Our stretch film quotations state the thickness in microns, the width, the roll weight and the core weight, and the pre-stretch the film is engineered for. Roll weight matters: a “15 kg roll” that contains 13.5 kg of film and 1.5 kg of core is a 10% price rise nobody wrote down.
Send us your current specification and pallet count and we will run this calculation against what you buy today. If the answer is that your existing supplier is already competitive, that is what we will tell you — it is a shorter conversation than the alternative and it happens more often than you would expect.