When you calculate shipping weight, the box itself counts. A large 5-ply carton can weigh more than a kilogram, which adds up across hundreds of shipments. Box weight depends on its size and the paper used. This guide explains how much a cardboard box weighs and how to estimate it, with our free Box Weight Calculator.
The basic method
Box weight = Board area (m²) × Combined board weight (g/m²)
Step 1: Board area
For a regular slotted carton (RSC), the flat blank is approximately:
- Blank length = 2 × (L + W) + glue flap (about 4 cm)
- Blank width = H + W (top and bottom flaps each half the width)
Example: a 40 × 30 × 30 cm box: blank = (2 × 70 + 4) × (30 + 30) = 144 × 60 cm = 0.864 m².
Step 2: Combined GSM
Corrugated board is made of liners and fluted medium. The medium is longer than the board because of the waves, so its weight is multiplied by a take-up factor (about 1.4 to 1.5 for common flutes).
Example 3-ply: 150 gsm liner + 120 gsm medium × 1.4 + 150 gsm liner = 150 + 168 + 150 = 468 g/m² (plus a little glue).
Step 3: Multiply
0.864 × 468 = 404 g, so the box weighs about 0.4 kg.
Typical weights
| Box (cm) | 3-ply | 5-ply |
|---|---|---|
| 30 × 20 × 15 | 0.15 to 0.2 kg | 0.3 to 0.4 kg |
| 40 × 30 × 30 | 0.35 to 0.45 kg | 0.7 to 0.9 kg |
| 60 × 40 × 40 | 0.7 to 0.9 kg | 1.3 to 1.7 kg |
Actual weights depend on paper grades, so weigh a sample.
Why it matters
- Shipping cost: box weight adds to gross weight.
- Declarations: export documents show net and gross weight; read tare, gross and net weight.
- Costing: board cost is often priced per kg; see the Packaging Cost Calculator.
For board grades, see the Corrugated Board Calculator.
Frequently asked questions
How heavy is a typical cardboard box?
A medium 3-ply box of 40 × 30 × 30 cm weighs about 0.35 to 0.45 kg.
What is GSM?
Grams per square metre, the weight of paper or board.
Does a 5-ply box weigh double a 3-ply box?
Roughly, as it has more layers of paper.