Plastic Film Weight Calculator
From width, thickness, length and resin, get the roll weight, GSM (g/m²) and yield (m²/kg) — the numbers film buyers and converters price on. Updates as you type.
Existing stretch-wrap example: a 500 mm wide, 20 µm thick, 1000 m long PE film at 920 kg/m³ weighs 9.2 kg net, with grammage 18.4 g/m² and yield about 54.35 m²/kg.
How film weight is calculated
Roll weight = width × length × thickness × density. Keep the units consistent — width and length in metres, thickness in metres (microns ÷ 1,000,000), density in kg/m³. From the same inputs you also get:
- GSM (g/m²) = thickness × density — the grammage buyers quote.
- Yield (m²/kg) = 1 ÷ (GSM ÷ 1000) — how much film you get per kilo, the number that decides cost per square metre.
Because price is usually per kilo but you buy area, yield is the figure that really compares two films.
Worked example — 50 µm LDPE film
- Width 1.2 m × length 2,000 m gives 2,400 m².
- Thickness 50 µm × density 920 kg/m³ gives 46 g/m².
- Area × grammage gives 110.4 kg per roll.
- Yield is 1,000 ÷ 46 = 21.74 m²/kg.
Assumptions and common errors
- The result is net film weight; it excludes cores, packaging, ink, adhesive and coatings unless their mass is included separately.
- Nominal thickness can differ from measured average thickness across the web.
- Use the resin grade’s technical data sheet when density matters; the presets are typical values, not grade specifications.
- Do not enter density in g/cm³—the field expects kg/m³. For example, 0.92 g/cm³ is 920 kg/m³.
For the unit derivation and a cost-per-area workflow, read film weight from thickness and density. See MatQuo’s calculation methodology.
Related tools
Measuring tools
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Film measurements for packaging work
UK film specifications may use microns, millimetres or gauge terminology. This calculator expects thickness in microns, width in millimetres and length in metres. A micron is one thousandth of a millimetre. Enter 20 for a 20 µm film, not 0.020. Use the web’s full width; a folded tube may need unfolding before its film area can be calculated. All examples below are hypothetical material calculations, not supplier specifications.
Example: pallet stretch wrap
For a warehouse roll, assume a 500 mm web, 20 µm thickness, 1000 m length and the calculator’s 920 kg/m³ PE density. Width becomes 0.5 m and thickness becomes 0.000020 m. Area is 500 m²; multiplying area, thickness and density gives 9.2 kg of plastic. Grammage is 18.4 g/m² and yield is about 54.35 m²/kg. That mass excludes the cardboard core, labels and outer packaging.
Example: BOPP for biscuit packaging
For a hypothetical biscuit-packaging web, take 400 mm width, 30 µm thickness and 1500 m length. Select PP at 905 kg/m³. The area is 600 m², grammage 27.15 g/m² and calculated film mass 16.29 kg. Enter the actual grade density if the film includes a filled layer or a coating. A generic PP preset cannot account for every laminate construction.
Film types to identify on the specification
LDPE and LLDPE stretch film are relevant when estimating pallet-wrap consumption; BOPP is a useful example for printed snack or bakery wrappers. PET can be a layer in a laminate rather than the whole structure. These are application examples, not a claim about national market shares. Distinguish base resin, orientation, coatings and layers before choosing a density. For multilayer film, use a density appropriate to the complete structure or calculate the layers separately.
Plastic film calculation questions
How do I calculate plastic film roll weight?
Multiply film width, length, thickness and density in consistent units to obtain net plastic mass. Use metres for width and length, convert microns to metres, and enter density in kg/m³. The result excludes the cardboard core and packaging. Use representative thickness and the actual structure's density when checking a roll against a specification.
- Measure film width, original roll length and representative thickness.
- Select the appropriate density or enter the grade's value in kg/m³.
- Read net mass, GSM and yield; add core and packaging mass separately for shipping.
How is the GSM of plastic film calculated?
Film GSM is its thickness in metres multiplied by density in kg/m³ and by 1000, giving grams per square metre. In the existing stretch-wrap example, 20 µm PE at 920 kg/m³ gives 18.4 g/m². Grammage links area to mass; coatings and laminates need inputs appropriate to their complete structure.
Which density should I use for LDPE, HDPE or PP film?
The calculator's typical presets are 0.92 g/cm³ for LDPE and LLDPE, 0.95 for HDPE and 0.905 for PP. They are planning values, rather than grade specifications. Prefer the actual technical data sheet when available. A coating, filled layer or laminate can make the finished structure differ from the base resin preset.
| Typical material preset | Density |
|---|---|
| LDPE / LLDPE | 0.92 g/cm³ |
| HDPE | 0.95 g/cm³ |
| PP | 0.905 g/cm³ |
| PET | 1.38 g/cm³ |
| PVC | 1.40 g/cm³ |
Does pre-stretch change the purchased roll weight?
Pre-stretch changes the thickness and covered area during wrapping, but does not create additional plastic mass. Calculate the purchased roll using its original dimensions before stretching. The net roll weight alone does not predict consumption per pallet, which also depends on overlaps, wrapping turns and machine settings for the particular load.
How do I include the cardboard core in shipping weight?
Add a measured or verified empty-core tare separately to the calculated net film mass to estimate shipping weight. Include labels, plugs and outer packaging when relevant. Compare a scale reading with net film only after subtracting those components, and check representative thickness, length and density if a difference remains.
Can I convert a film price per kilogram to a price per square metre?
Divide your own price per kilogram by the film yield in m²/kg to obtain material cost per square metre. The calculator supplies the area-to-mass relationship, rather than a market price. Account separately for scrap, printing, conversion and taxes, and keep the same thickness and density assumptions when comparing alternative films.
Take several measurements across the width and along the roll. An appropriate mean thickness is more useful than one unusually thick edge reading. Record the measurement method and compare the result with the specification’s tolerances.