The purchasing question
Two offers expressed per running metre can cover different quantities of film. A wider web contains more square metres at the same length. Comparing the running-metre prices directly can therefore select the wrong supplier, even when the material structure and GSM match.
Calculation method
Area per running metre equals width in metres. Divide price per running metre by width to obtain price per square metre. Multiply area price by 1,000 ÷ GSM when a kilogram comparison is also needed. Compare full purchased width and useful width separately if edge trim differs.
Worked example
Supplier A quotes €0.18/m for a 900 mm web; supplier B quotes €0.17/m for an 800 mm web. A is €0.20/m², while B is €0.2125/m². For the same 9,000 m² requirement, the material totals are €1,800 and €1,912.50 before freight or losses.
The cheaper running-metre offer is more expensive per area in this example. However, production lanes may make a particular width more efficient. Compare the cost per accepted pack when different widths produce different trim or layout yields.
Checks before using the result
- Convert millimetres to metres before dividing.
- Verify that the machine can use the quoted width.
- Include any unusable edge area in production costing.
Common questions
Should I request identical web widths from all suppliers?
That simplifies price comparison when the production layout is fixed. If widths differ, compare both area price and usable output from each layout.