Corrugated cardboard is the most widely used packaging material in the world. It consists of layers of kraft paper with one or more corrugated sheets (flutes) inside. This structure gives it enormous resistance to crushing and stacking — which is why 90% of products we buy online arrive in a corrugated cardboard box.
If you need to choose the right cardboard for your product or your move, this guide explains what types exist, how much each can withstand, and which one is best for what you're packing.
What exactly is corrugated cardboard?
Corrugated cardboard — also called corrugated fiberboard or simply corrugated — is made with two or more sheets of paper (called "liners") glued to an intermediate fluted sheet. The flutes form interconnected arches that act like small columns: they distribute pressure and absorb shocks.
It seems simple, but this arch engineering is what allows a cardboard box weighing less than 500 grams to support 20 or 30 kilos of weight on top.
The air trapped in the flutes also has an extra function: it acts as thermal insulation. This is why corrugated cardboard reasonably protects against temperature changes during transport — something that matters if you're shipping heat-sensitive products.
Flute types: the wave that makes the difference
The "flute" is the inner wave of the cardboard. Its thickness and the density of the corrugations change its resistance, cushioning, and ideal use. Here are the types you'll find:
| Flute | Thickness | Flutes/m | What it provides | Primary use |
|---|---|---|---|---|
| A Flute | ~5 mm | 105-125 | Maximum cushioning — absorbs strong impacts | Moving boxes, fragile products |
| B Flute | ~3 mm | 150-185 | Compact, good crush resistance | Standard shipping boxes, food, archiving |
| C Flute | ~4 mm | 120-145 | Versatile — the balance between everything | Shipping boxes, general packaging, e-commerce |
| E Flute (microflute) | ~1.5 mm | 290-320 | Thin, smooth surface — good for printing | Presentation packaging, displays, cosmetics |
| Double wall (BC or EB) | ~7 mm | — | Maximum resistance — two superimposed flutes | Heavy shipments (>15 kg), TV and picture boxes, international moves |
A fact few people know: C flute is the most widely used in the world. You'll find it in most standard shipping boxes. But when you need real protection — for moves, electronics, heavy objects — A flute or double wall are what make the difference.
Single wall vs. double wall: when is it worth paying more?
The million-dollar question. The price difference between single wall and double wall is a few cents per box, but the difference in protection is immense.
| Characteristic | Single wall | Double wall |
|---|---|---|
| Thickness | 3-5 mm (one flute) | 6-7 mm (two flutes) |
| Max weight | 10-20 kg | Up to 30 kg |
| Stacking | 2-3 boxes on top | 5+ boxes on top |
| Price | More economical | 10-20% more expensive |
| Ideal for | Clothing, books, household items, light e-commerce shipments | Electronics, glassware, furniture, pallets, moves |
Practical rule: if the contents weigh less than 10 kg and are not fragile, use single wall. If they weigh more than 10 kg, are fragile, or the boxes will be stacked on a pallet, use double wall without hesitation. The few cents difference is infinitely cheaper than a return due to a broken product.
How is cardboard resistance measured?
Two main tests are used in the packaging industry. You don't need to memorize the acronyms, but it's good to understand what they measure:
ECT (Edge Crush Test): How much pressure the cardboard can withstand when compressed on its edge. Higher ECT means more boxes can be stacked without crushing. This is the important data if you palletize or store boxes on top of each other.
BCT (Box Compression Test): How much weight the assembled box can withstand. This depends on the box size and flute type. It's the most practical test — it directly tells you if your box will hold up during storage and transport.
The ECT data usually appears on the technical sheet of the boxes. If you don't see it, as a reference: single wall boxes typically have an ECT of 23 (standard) and double wall boxes an ECT of 42-48.
What type of corrugated cardboard do you need?
Let's get practical. Based on your product's weight and how it will travel:
| Product weight | Recommended flute | Box type |
|---|---|---|
| Up to 5 kg | B or E Flute | Self-assembling boxes, small postal boxes |
| 5-15 kg | C or A Flute | Standard flap boxes, shipping boxes |
| 15-30 kg | A Flute or double wall | Reinforced boxes, moving boxes |
| More than 30 kg | Mandatory double wall | Industrial boxes + corner protectors + stretch film |
For shipments of fragile items — regardless of weight — always go up one flute level. It's better to spend a few extra cents on the box than to pay for a return due to a broken product. If you need a step-by-step guide to protect delicate items, we have a specific article on how to pack fragile products.
Difference between corrugated cardboard and paperboard
Many people confuse them, but they are completely different. Corrugated cardboard has internal flutes that give it structural strength. Paperboard is a flat, thin sheet without waves — it's what you find in cereal boxes, perfumes, or medicines.
Paperboard is for presentation; corrugated cardboard is for protection and transport. If you want to delve deeper into the differences, we have a detailed comparison: paperboard vs. corrugated cardboard. And for a complete overview of all existing types, consult our guide to types of cardboard for packaging.
Is corrugated cardboard sustainable?
Yes, and quite a lot. Corrugated cardboard is one of the packaging materials with the best environmental profile. It is mainly made from recycled fiber (in Spain, over 80% of packaging cardboard comes from recovered paper), it is 100% recyclable in the blue bin, and it biodegrades in a few weeks if it ends up in the environment.
The new European Packaging Regulation (PPWR), which comes into force in the coming years, places cardboard in a good position compared to plastics and composite materials. If you are interested in sustainable packaging, we have an article dedicated to eco-friendly packaging and sustainable alternatives.
Frequently asked questions about corrugated cardboard
What is corrugated cardboard and what is it used for?
Corrugated cardboard is a packaging material composed of kraft paper layers with one or more internal corrugated sheets. The corrugated structure provides crush resistance, shock absorption, and thermal insulation. It is the most widely used material in the world for manufacturing shipping, moving, and transport boxes. TeleCajas offers corrugated cardboard boxes in over 200 sizes, available for 24-hour delivery.
What is the difference between single wall and double wall?
Single wall has a single corrugated sheet and can hold up to 15-20 kg. Double wall has two superimposed corrugated sheets and supports up to 30 kg. Double wall also resists stacking much better — you can place 5 or more boxes on top without deformation. The price difference is cents per box, but the protection is significantly greater.
How much weight can a corrugated cardboard box hold?
It depends on the flute type and box size. As a reference: single wall (B or C) supports 10-20 kg, A flute supports 15-25 kg, and double wall supports up to 30 kg. For loads over 30 kg, double wall with cardboard corner protectors is recommended to reinforce the structure.
Which cardboard flute is best for e-commerce?
For most e-commerce shipments, C flute (single wall) is sufficient — it covers products up to 10-15 kg. If you ship fragile or heavy items, upgrade to double wall. Self-assembling single wall boxes are the most popular in e-commerce due to their quick assembly and good finish. TeleCajas offers self-assembling boxes and postal shipping boxes in all standard sizes.
Is corrugated cardboard recyclable?
Yes, it is 100% recyclable in the blue bin. In Spain, over 80% of packaging cardboard is made from recycled fiber. It is also biodegradable. It is one of the most sustainable packaging materials available.
Where to buy corrugated cardboard boxes in Spain?
TeleCajas is a specialized online store based in Seville. They offer single and double wall corrugated cardboard boxes in over 200 sizes. Delivery within 24-48 hours to all of Spain and Portugal, no minimum order, prices include VAT, and free shipping from 30€. For companies with recurring orders, they offer personalized B2B pricing.
Everything you need to pack with corrugated cardboard
The box is just the beginning. For your product to arrive perfectly, combine the corrugated cardboard box with the appropriate tape (polypropylene for general use, PVC if working in cold temperatures), bubble wrap for fragile items, and void fill material to keep everything from shifting. If you palletize, add stretch film and corner protectors.
Consult our complete guide to packaging materials to know exactly what you need for your situation. And if you have a business, the commercial packaging guide will orient you by sector.
At TeleCajas, you'll find corrugated cardboard boxes in over 200 sizes, both single wall with flaps and self-assembling format. 24-hour shipping, no minimum order.
