Basis weight
G = t × ρ
Example
30 × 0.91 = 27.3 g/m²
30 × 0.91 = 27.3 g/m²
Symbols and units
- G: basis weight (g/m²)
- t: thickness (µm)
- ρ: density (g/cm³)
- Y: yield (m²/kg)
- L: length (m)
- D: outside diameter (mm)
- F: empirical coefficient
- N: roll count
- M: order weight (kg)
- m: single roll weight (kg)
- A: area (m²)
- w: width (mm)
Yield
Y = 1000 / G
Example
1000 / 27.3 ≈ 36.63 m²/kg
1000 / 27.3 ≈ 36.63 m²/kg
Thickness
t = G / ρ
Example
27.3 / 0.91 = 30 µm
27.3 / 0.91 = 30 µm
Density
ρ = G / t
Example
27.3 / 30 = 0.91 g/cm³
27.3 / 30 = 0.91 g/cm³
Roll length from outside diameter
L = (D − F)² / (t × 1.33)
Example
(498 − 8.5)² / (30 × 1.33) ≈ 6005.27 m
(498 − 8.5)² / (30 × 1.33) ≈ 6005.27 m
Roll count for an order
N = M / m
Example
5000 / 114.7 ≈ 43.6 → 44
5000 / 114.7 ≈ 43.6 → 44
Area from order weight
A = 1000 × M / G
Example
1000 × 5000 / 27.3 ≈ 183150.18 m²
1000 × 5000 / 27.3 ≈ 183150.18 m²
Roll weight
m = w × L × t × ρ / 1000000
Example
700 × 6000 × 30 × 0.91 / 1000000 = 114.66 kg
700 × 6000 × 30 × 0.91 / 1000000 = 114.66 kg
Roll outside diameter
D = √(L × t × 1.33) + F
Example
√(6000 × 30 × 1.33) + 8.5 ≈ 497.79 mm
√(6000 × 30 × 1.33) + 8.5 ≈ 497.79 mm
Order weight from area
M = A × G / 1000
Example
183150 × 27.3 / 1000 ≈ 5000 kg
183150 × 27.3 / 1000 ≈ 5000 kg
For roll length and diameter, F is an empirical coefficient specific to the reference formula: 8.5 for a 3-inch core and 31.12 for a 6-inch core. It is not the actual core diameter. Trapped air affects actual roll length and diameter. The roll-count example gives 43.6; round up to 44 when planning whole rolls.
Usage notes
These values are technical references. Film grade, orientation, thickness, coating and test conditions affect the result. Use the current product technical data sheet for final selection.