The Basics
Single wall corrugated has one layer of fluting between two liners (three layers total). Double wall has two layers of fluting separated by a liner (five layers total). The extra layers in double wall roughly double the crush resistance and stacking strength.
When Single Wall Is Enough
For the vast majority of shipping applications, single wall corrugated is perfectly adequate. If your product weighs under 40 pounds, ships domestically via parcel carriers, and is not unusually fragile, single wall in 32 ECT or 44 ECT is the standard choice.
Single wall is lighter, cheaper, and easier to fold and tape. It also takes up less storage space when knocked-down (stored flat). For e-commerce, retail shipping, and general business use, single wall is the workhorse.
When You Need Double Wall
Double wall earns its premium in specific scenarios:
- Heavy products (40-100 lbs per box) that need superior bottom and side wall support.
- Fragile high-value items where the cost of damage far exceeds the cost of better packaging.
- Stacking in warehouses — if loaded boxes will be stacked 3+ high for extended periods.
- Rough handling environments — freight shipping, international transport, or situations with multiple transfers.
- Long-term storage where boxes must maintain integrity for months.
The Cost Equation
Double wall boxes typically cost 40-60% more than equivalent single wall. But the cost difference shrinks dramatically when buying used: a used double wall box from Portland Boxes often costs the same as a new single wall from a conventional supplier.
If you are on the fence, buying used double wall gives you the strength upgrade at the price of new single wall.
The Verdict
Most businesses over-buy on box strength because they have never had anyone explain the ratings clearly. If you are shipping t-shirts in double wall boxes, you are wasting money. If you are shipping power tools in single wall, you are risking damage claims.
Match the box to the job. When in doubt, ask us — we have graded and shipped millions of boxes and can tell you exactly what you need.