Box Area Calculator (Blank / Die-line)
A carton box's area is the blank (die-line) area it covers when flattened, and it is the basis of material cost. For a standard glued/locked box the cutting width = 2 × (Width + Length) + glue flap, the cutting height = Height + 2 × closing flap; blank area (m²) = (cutting width × cutting height) ÷ 10,000 (dimensions in cm).
Blank-area formula
Cutting width = 2 × (En + Boy) + glue flap
Cutting height = Height + 2 × closing flap
Blank area (m²) = (cutting width × cutting height) ÷ 10.000
Worked example
For a 20 × 15 × 10 cm box with a 1.5 cm glue flap and closing flap = length (15 cm): cutting width = 2 × (20 + 15) + 1.5 = 71.5 cm, cutting height = 10 + 2 × 15 = 40 cm. Blank area = (71.5 × 40) ÷ 10,000 ≈ 0.286 m²/pc. Assembled surface area = 2 × (20·15 + 20·10 + 15·10) ÷ 10,000 = 0.13 m².
Calculator
Enter width, length and height.
This is an approximate blank size for a standard glued/locked carton. The exact value depends on the box model and its die-line.
Frequently asked questions
How do I calculate a carton box's area?
Find the box blank (die-line): for a standard glued box the cutting width = 2 × (Width + Length) + glue flap, and the cutting height = Height + 2 × closing flap. Blank area (m²) = (cutting width × cutting height) ÷ 10,000, with dimensions in centimetres.
What is the difference between blank area and surface area?
Assembled surface area is the sum of the outer faces of the built box (2 × (W·L + W·H + L·H)) and gives the print/lamination coverage. The blank area is the flat cutting area including glue and closing flaps; it is what drives material consumption.
How large are the glue and closing flaps?
The glue flap is typically 1.2-2 cm. The closing (top/bottom) flap depends on the box model; for glued and locked-lid cartons it is usually about the box depth (length). The exact value depends on the box die-line.
How do I turn this area into a cost?
Blank area (m²) × grammage (kg/m²) × price per kg with a waste multiplier gives the material cost. Add printing, cutting, tooling share and labour, then apply the margin for the unit selling price. You can enter this m² value into the packaging cost calculator.