Corrugated Box
Also known as: Cardboard Box, Shipping Box, Carton
Definition
A corrugated box is the standard shipping container used for most packages. Made from corrugated fiberboard—a fluted sheet sandwiched between two flat liner boards—these boxes provide excellent protection while remaining lightweight and recyclable.
Anatomy of a Corrugated Box
Three layers:
- Outside liner - Smooth exterior surface
- Fluting (medium) - Wavy inner layer for cushioning
- Inside liner - Interior smooth surface
The fluted design creates air columns that absorb impacts and provide insulation.
Corrugated Flute Types
| Flute | Thickness | Use Case |
|---|---|---|
| A-Flute | 5mm | Heavy items, max cushioning |
| B-Flute | 3mm | Standard shipping, die-cuts |
| C-Flute | 4mm | Most common, good balance |
| E-Flute | 1.5mm | Retail packaging, printing |
| F-Flute | 0.8mm | Small items, folding cartons |
C-Flute is the default for most shipping boxes.
Wall Types
Single-Wall
- One layer of fluting
- Standard for packages under 40 lbs
- Most economical
- Adequate for most shipments
Double-Wall
- Two layers of fluting
- For heavy items (40-80 lbs)
- Extra crush resistance
- Better stacking strength
Triple-Wall
- Three layers of fluting
- Industrial/freight use
- Can replace wooden crates
- Rarely needed for parcel
Box Sizing
Standard box dimensions are expressed as: Length × Width × Height (L × W × H)
Length = longest side Width = shorter side Height = distance between openings
Always measure inside dimensions for fit.
Common Box Sizes
| Size | Dimensions | Use Case |
|---|---|---|
| Small | 8" × 6" × 4" | Small items, accessories |
| Medium | 12" × 10" × 8" | Shoes, electronics |
| Large | 18" × 14" × 12" | Multiple items, bulky goods |
| XL | 24" × 18" × 18" | Large products, freight |
Burst Strength vs. Edge Crush
Burst Strength (Mullen)
- Measures puncture resistance
- Expressed in PSI
- Good for rough handling
Edge Crush Test (ECT)
- Measures stacking strength
- Expressed in lbs per inch
- Better for palletized freight
| ECT Rating | Max Stacking Weight |
|---|---|
| 32 ECT | ~40 lbs |
| 44 ECT | ~65 lbs |
| 48 ECT | ~80 lbs |
Box Selection Tips
- Size appropriately - 2-3" clearance per side for cushioning
- Match weight to strength - Heavy items need double-wall
- Consider stacking - Higher ECT for bottom boxes
- New boxes for fragile - Used boxes lose strength
- Avoid oversizing - Higher DIM weight = higher cost
Corrugated Box Sustainability
- 70%+ of corrugated is recycled content
- Nearly 100% recyclable
- Biodegradable
- Renewable resource (paper/pulp)
- Most sustainable rigid packaging option
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