A worked example
10,017 kg of net fabric, 290 g/m² and 190 cm wide: approximately 18,179.67 metres and 34,541.38 m². One metre weighs 0.551 kg. A 20 kg roll would be about 36.30 metres; 20 kg is only an example.
m² = kg × 1000 ÷ g/m²
Metres = m² ÷ (width cm ÷ 100)
Metres = m² ÷ (width cm ÷ 100)
Use grams per square metre, not grams per linear metre. Assumes constant width and weight per area. Core, packaging, moisture, shrinkage and waste are excluded. Dividing by roll count gives an average, not proof that every roll is equal.