Stretch film: gross and net weight

Updated: 30.09.2026

Stretch film is usually sold by the roll, but compared per kilogram of film. The catch is that the weight of a roll also includes the cardboard core the film is wound on. If you do not separate the core from the film, two rolls that look the same may contain different amounts of usable film. This guide shows how to do the calculation.

Three different weights

What matters to you is the net weight: only the film is used for wrapping. The core ends up as waste.

On each product page we state the net weight and, where relevant, the gross weight and core weight. If a supplier only says "2.5 kg roll", ask whether that is gross or net.

Why the core matters

Cores do not all weigh the same. Their weight depends on:

• the inner diameter: hand rolls usually have a thinner core than rolls for wrapping machines;
• the wall thickness of the core;
• the length of the core, which is roughly equal to the film width (for example 500 mm).

On a hand roll, the core can account for a significant share of the gross weight. A heavier core means less film for the same gross weight.

Price per net kilogram

The formula is simple:

price per net kg = roll price ÷ net weight

Example with hypothetical values, for two rolls of the same width (500 mm) and thickness (23 µm):

Compared per gross kilogram, roll A looks cheaper. Per net kilogram, roll B is better value, even though it costs more per roll.

How many metres of film are on a roll

The film length on a roll can be estimated from the net weight, width and thickness. Stretch film is usually made from linear low-density polyethylene (LLDPE), with a density of about 0.92 g/cm³.

length (m) ≈ net weight (kg) ÷ [width (m) × thickness (µm) × 0.00092]

For roll A (2.00 kg net, 0.5 m, 23 µm):

• weight of one metre of film: 0.5 × 23 × 0.00092 = 0.01058 kg, i.e. about 10.6 g;
• length: 2.00 ÷ 0.01058 ≈ 189 m.

For roll B (2.15 kg net): 2.15 ÷ 0.01058 ≈ 203 m.

The result is an estimate. The actual thickness has a manufacturing tolerance, and density varies slightly with the formulation. If the product page states the length, use the declared value.

Price per metre and thickness

If you compare rolls of different thicknesses, the price per kilogram is no longer enough. A thinner film gives more metres per kilogram, but each layer holds less. In that case, compare:

1. the price per metre of film: roll price ÷ length;
2. how many layers are needed to stabilise the load;
3. the cost of film used per wrapped pallet.

The values in the table are calculated with a density of 0.92 g/cm³ and are for comparison only.

Cost per pallet

For a business, the most useful indicator is the film cost per pallet. It is easy to find:

1. weigh a roll before you start;
2. wrap a known number of pallets (for example 10), the way you normally work;
3. weigh the roll again; the difference is the film used;
4. divide by the number of pallets and multiply by the price per net kilogram.

Hypothetical example: 1.20 kg was used for 10 pallets, i.e. 0.12 kg per pallet. At 17.21 lei per net kg, the cost is about 2.07 lei per pallet, excluding VAT.

Hand film or machine film

• Hand film is applied by hand, with or without a dispenser. The rolls are lighter so they can be handled easily.
• Machine film for wrapping machines comes in heavier rolls with cores sized for the machine's mandrel. Check that the core inner diameter and the width are compatible with your machine.

The characteristics of each type are stated on the product page.

In short

1. Check whether the stated weight is gross or net.
2. Compare rolls by price per net kilogram.
3. For different thicknesses, compare price per metre and the number of layers needed.
4. For professional use, measure the film cost per pallet.