A carton’s basic weight is the number that determines how much paper goes into each box — and paper is the single biggest cost component in a corrugated sheet. Get it wrong, and the price you quote is off: either too expensive and you lose the tender, or too cheap and your margin is gone. Here’s how to work it out correctly.
Why it isn’t as simple as adding up the basis weights
A corrugated sheet has several layers of paper — the outer liner, the medium (the fluted layer), and the inner liner — each with a different basis weight. If you just add up the basis weight of each layer, the result is wrong, because the fluted medium layer needs more paper than its flat surface suggests.
For example: to cover 1 square metre of surface, a straightened-out B-flute medium is actually 1.32 square metres long. That’s why the medium’s basis weight has to be multiplied by a factor — the Take Up Factor (TUF).
Take Up Factor table per flute
The Take Up Factor is the ratio of the paper’s length inside the flute structure compared to the length of its flat sheet:
| Flute type | Take Up Factor (TUF) |
|---|---|
| A-flute | 1.54 |
| B-flute | 1.32 |
| C-flute | 1.44 |
| E-flute | 1.27 |
The liner (the flat surface) isn’t multiplied by anything — its factor is 1.00.
The formula
Basic weight per layer = basis weight × Take Up Factor
Total basic weight = the sum of the basic weights of all layers
Worked example
Take a double wall carton with a K150 / M125×3 / K125 structure (a C/B flute combination), sized 100 × 100 cm:
| Layer | Basis weight | TUF | Basic weight |
|---|---|---|---|
| K150 (outer liner) | 150 gsm | 1.00 | 150 gsm |
| M125 (medium, C-flute) | 125 gsm | 1.44 | 180 gsm |
| M125 (medium, B-flute) | 125 gsm | 1.32 | 165 gsm |
| M125 (medium, C-flute) | 125 gsm | 1.44 | 180 gsm |
| K125 (inner liner) | 125 gsm | 1.00 | 125 gsm |
Total basic weight = 150 + 180 + 165 + 180 + 125 = 800 gsm.
That 800 gsm figure is the basis for calculating paper requirement, shipping weight, and ultimately the price per box.
Why this number matters
- Cost estimation. Basic weight × box area = paper requirement. This is what translates a part spec into a price.
- Logistics. Basic weight determines the total shipment weight — which affects freight cost and truck-loading efficiency.
- Strength. The right structure and basis weight keep a box stack-resistant without paying for excess paper.
- Material efficiency. Knowing the basic weight means not over-speccing — less paper, less cost, less waste.
At JMP, this basic-weight calculation is exactly what we use to convert your part spec into a structure and a price — built from zero, not pulled off a catalogue. Have a part that needs calculating? Send us the part details or a drawing, and we’ll run the numbers first.
See also: carton box flute guide · custom corrugated carton boxes.
Source: PT Jaya Mandiri Packaging (JMP) — carton box & polybag manufacturer for the automotive industry since 1990. jayamandiripackaging.com
