Method / assumptions / examples
How this calculation works
The result is deterministic: the same measurements always return the same estimate. Here is the relationship and where real-world results can differ.
01
Formula
Weight (kg) = length (m) × width (m) × GSM ÷ 1,000
GSM is mass per square metre, so multiplying converted web area by GSM gives grams. The result excludes the core, packaging, splices, and excess winding allowance.
02
Worked example
Examples
Standard estimate
A 5,000 ft × 12 in web at 80 g/m² contains about 37.2 kg (82.0 lb) of material.
03
Common mistakes
What to check before using the result
- Use the combined construction GSM for laminates rather than a single layer’s basis weight.
- Add core and packaging weights separately when estimating shipping or lifting requirements.
- Actual moisture content and coating variation may move measured weight away from the estimate.
04
FAQ
Frequently asked questions
Is the core included?
No. This calculates net web weight. Add the known tare weight of the core and any packaging for gross roll weight.
What GSM should I use for a laminate?
Use the total finished construction weight per square metre, including films, paper, adhesive, and coatings when known.