Film kg to meter calculator
Convert between kilograms and meters of film, in either direction, using your own material properties.
Film is bought by weight and run by length. Every planner, estimator and store keeper needs to move between the two, and the conversion depends entirely on the material.
Rather than assume a density, this calculator asks for the properties of the film you are actually running. Enter thickness and density, or enter GSM directly if your supplier quotes it that way.
Calculator
How to use it
- Enter Direction
- Enter Amount in kg or m. Kilograms or meters, matching the direction above
- Enter Web width in mm
- Enter Material basis
- Enter Thickness in micron. Used when basis is thickness and density
- Enter Density in g/cm³. PE around 0.92, PP around 0.90, PET around 1.40. Confirm with your supplier.
- Enter GSM in g/m². Used when basis is GSM. For a laminate, enter the total structure GSM.
- Enter Waste allowance in %
Formula
Worked example
A 50 micron PE film, 800 mm wide, density 0.92 g/cm³, converting 500 kg:
- GSM = 50 × 0.92 =
46 g/m² - Weight per meter = 46 × 0.8 ÷ 1000 =
0.0368 kg/m - Length = 500 ÷ 0.0368 =
13,587 m
Assumptions
- Thickness × density gives GSM because one micron of a material at 1 g/cm³ weighs exactly one gram per square meter. The conversion is exact; the inputs are what carry uncertainty.
- Width is the full roll width. If you are working from a slit width, enter the slit width.
- For a laminate, the simplest reliable approach is to enter the total structure GSM from your supplier rather than trying to model each layer and adhesive.
Limitations
Every calculator on this site gives a planning figure, not a production guarantee. Check the result against your own records before committing material or money to it.
- Nominal thickness is not actual thickness. Films run to a tolerance, and a film at the top of its tolerance band can be several percent heavier than the nominal calculation suggests.
- Coatings, adhesive, metallising and print all add weight that a single thickness and density figure does not capture.
- Core weight is not included. A roll weight from the weighbridge includes the core, this calculation does not.
Common mistakes
- Using a generic density for every film. PE, PP and PET differ enough to throw planning out significantly.
- Entering micron in the GSM field or the other way round. Check the basis selector matches the number you typed.
- Comparing a calculated roll weight with a weighed roll and assuming the calculation is wrong. Check the core, the tolerance and any coating first.
Frequently asked questions
How do you convert kg to meters for film?
Work out GSM from thickness times density, multiply by the width in meters and divide by 1000 to get kilograms per running meter, then divide your weight by that figure. This calculator does all three steps and shows the intermediate values.
What density should I use?
Use the figure from your supplier for the specific grade. As a general orientation polyethylene sits around 0.92 g/cm³, polypropylene around 0.90 and PET around 1.40, but grades vary and those numbers should never be used for contractual calculations.
Can I use this for laminates?
Yes, by entering the total structure GSM rather than thickness and density. Adhesive layers and coatings mean a laminate is not simply the sum of its film thicknesses.
Why does my calculated weight differ from the actual roll weight?
Common reasons are thickness tolerance, the core, coating or metallising weight, and moisture in paper based structures. The formula is exact, so a difference points at the inputs or at something not included in them.