How to Choose the Right Cardboard Boxes
Table of Contents
Why the Quality of your Cardboard Box Matters
Cardboard boxes may appear simple at first glance, yet they are the foundation of global packaging. Every day, millions of goods are shipped, stored, and delivered safely because of corrugated cardboard – a material that balances strength, cost-efficiency, and environmental responsibility. From online retailers and manufacturers to food distributors and removal companies, cardboard remains the packaging of choice across almost every industry.
Corrugated packaging first emerged in the 19th century, when it’s fluted structure was developed to provide additional cushioning and strength over flat paperboard. Since then, it has become the world’s most widely used shipping container. It’s success lies in it’s versatility: corrugated boxes can be manufactured in countless sizes, wall strengths, and styles, each suited to different applications.
At Packn, we supply a broad range of cardboard boxes to meet both business and personal needs. But we also believe that our customers should be empowered with knowledge. This guide aims to provide a simple introduction and overview to the different fluting types, corrugate materials, box styles (FEFCO) and their ideal applications. By the end, we hope you will have a clearer understanding of which type of cardboard box is right for your goods, ensuring both cost-effectiveness and reliable protection for your needs.
How to Measure a Cardboard Box
Choosing the correct box begins with accurate measurements. In the packaging industry, dimensions are always presented in order of length x width x height (L x W x H). These measurements always refer to the internal dimensions, which represent the usable space within the box that are available for your goods. Many people make the mistake of measuring the external dimensions of a box and, while this is fine as a general size guide, it can result in significant extra space when packing your goods, particularly if you’re looking for a snug fit for your goods.
- Length: the longest side of the box opening.
- Width: the shortest side of the box opening.
- Height (or Depth): the distance from the base to the top of the box.
- Multi-Depth: some boxes feature multi-depth or multi-score. This gives you the option to vary the depth of the box to one of the pre-scored dimensions.
Understanding this convention is essential, particularly if your boxes are being palletised or shipped with a courier. Carriers often calculate costs not only on the weight but also on the volume of the parcel. By ensuring you measure boxes internally, you avoid the risk of ordering packaging that does not fit your products properly and avoids incurring unexpected shipping surcharges.
As a practical example, a box measuring 305 x 229 x 152mm is perfectly suited to shipping A4-sized documents flat, while a 457 x 305 x 305mm carton provides ample space for bulkier goods.
It is also worth noting that external dimensions – which include the thickness of the cardboard walls – will always be slightly larger. This difference becomes more pronounced in double wall boxes, where the additional fluting adds extra bulk. For storage planning or pallet optimisation, external dimensions are often the more relevant figure.
Staff tip: always measure your goods first and leave a small allowance for protective packaging such as bubble wrap, packing paper, or void fill.
What’s the Difference Between Single Wall vs Double Wall Boxes?
One of the most important distinctions in corrugated packaging is the difference between single wall and double wall construction. First, it’s important to understand what “fluting” is.
What is Fluting?
Fluting is the wavy layer of paper that runs between the flat sheets (liners) in a cardboard box. It’s what gives corrugated board it’s strength. The waves act like little arches, helping the box absorb impacts and resist crushing during storage or transport. The direction the fluting runs i.e. vertical or horizontal, will significantly impact the boxes crush resistance.
What is a Single Wall Box?
Single wall boxes are composed of a single layer of fluting sandwiched between two liners. It is lightweight, cost-effective, and ideal for everyday packaging requirements such as shipping clothing, books, or non-fragile goods.
What is a Double Wall Box?
Double wall boxes consists of two layers of fluting and three liners. This additional structure provides enhanced strength, puncture resistance, and stacking capacity, making it suitable for heavier, bulkier, or fragile goods.
When Should I use Single or Double Wall?
The choice between single and double wall packaging usually comes down to weight and fragility. A small parcel containing lightweight products may not require the added protection of double wall. However, if goods are heavy, awkwardly shaped, or at risk of being stacked during transport, double wall packaging is the safer and most cost-effective choice in the long term.
Some practical examples include:
- An online retailer shipping soft items like clothing or linens can use single wall boxes without risk.
- A company shipping industrial machinery components or glassware will almost always require double wall boxes for protection during transit.
- For removals and storage, double wall cartons are the industry standard, as they withstand both heavy loads and repeated handling.
Staff tip: as a general rule of thumb, choose single wall for lighter, everyday goods, and double wall for heavier-duty shipping, removals or storage.
Types of Corrugated Fluting
At the core of corrugated cardboard’s strength lies it’s fluting – the wave-shaped layer between the liners. The height and pitch (spacing) of the fluting determines how well a box performs in terms of cushioning, stacking strength, and print quality.
The most common flute profiles for single wall boxes are:
| Fluting Name | Fluting Thickness | Typical Application |
| F Flute | ~1mm | Ultra-thin, excellent for small, lightweight retail cartons requiring detailed print |
| E Flute | ~1.5mm | Very thin, with a high flute count per foot. Provides a smooth surface for high-quality printing and often used in retail and presentation packaging. |
| R Flute | ~2.5mm | Very thin, with a high flute count per foot. Provides a smooth surface for high-quality printing and often used in retail and presentation packaging. R flute: ~2.5mm thick. R flute is trademarked by DS Smith Packaging, one of the largest multinational manufacturers of corrugated cartons in the UK. R flute was designed as a replacement for B flute. It offers better print performance, higher strength-to-weight ratio, and improved space efficiency. |
| P Flute | ~2.0 – 2.5mm | Developed by Saica, it aims to position itself between E and B flute. It reduces board weight while maintaining performance, supporting more sustainable packaging. |
| M Flute | ~2.3mm | VPK’s proprietary alternative to B flute. Similar benefits to R and P flutes, it offers reduced material use without compromising on stacking strength. |
| B Flute | 3mm | Rigid and compact, providing a flatter surface for printing. Common in retail packaging and smaller boxes. |
| C Flute | 4mm | A versatile all-rounder, balancing strength and cushioning. Frequently used in shipping cartons. |
| A Flute | 5mm | Thick and strong, providing excellent cushioning and stacking strength. Often used for fragile goods. |
Double wall corrugated boxes combine different single wall flute profiles to combine the best of both worlds. This results in enhanced cushioning and stacking strength. The most common flute profiles for double wall boxes are:
| Fluting Name | Fluting Thickness | Typical Application |
| EB Flute | ~4.5mm | Combines E and B flute, giving a strong stacking capacity with a fine print surface. |
| RB Flute | ~5mm | Combines R and B flute, a newer option that provides enhanced strength with improved material efficiency. |
| BC Flute | ~7mm | Combines B and C flute, offering strength and cushioning. Standard for shipping and removal boxes. |
| AC Flute | ~9mm | Combines A and C flute for heavy-duty export packaging. |
In practice, BC flute remains the most common double wall board for removals and shipping, while newer options like RB or EB are gaining ground in industries prioritising sustainability and print performance.
Thicker flutes generally provide greater cushioning and compression resistance, while thinner flutes provide smoother surfaces for high-quality printing and take up much less storage space (particularly when stacking pallets).
Types of Corrugated Material
Corrugated board is not only defined by it’s flute profile, but also by the paper liners that form the outer and inner surfaces. In the UK and European markets, the two most common liner types are Kraft (K) and Test (T).
Understanding the difference between these two liners will help businesses choose packaging that balances between their performance, appearance and environmental requirements and credentials.
Kraft Liner
Kraft paper is produced primarily from virgin wood fibres using the kraft pulping process. It is the stronger and more premium option, known for it’s durability, smooth finish, and resistance to tearing or puncturing. The key characteristics of a kraft liner are:
- High strength and rigidity, making it suitable for demanding applications.
- Naturally brown in colour, though it can be bleached for a white surface (also known as “White Kraft (WK)”.
- Resistance to moisture and rough handling.
- It is most commonly used on the outer face of boxes to provide a clean, strong presentation layer.
- Kraft has less ink absorption than Test, providing a greater print quality and finish.
Because it uses virgin fibre, kraft is less recycled than a test liner. However, it is sourced from managed forests and can itself be fully recycled multiple times. For packaging that must withstand export conditions or heavy-duty shipping, kraft-faced boxes are often preferred.
Test Liner
Test paper is produced from recycled fibres, making it a more environmentally efficient material. Although not as strong as virgin kraft, modern test liners are engineered to provide excellent performance for the majority of packaging applications. The key characteristics of a test liner are:
- Made from 100% recycled content.
- More cost-effective than kraft.
- Slightly rougher texture and less consistent surface.
- Suitable for most day-to-day packaging needs where extreme strength is not required.
- Test has greater ink absorption than Kraft, providing a lesser print quality and finish.
Test liners are commonly used for the inner face of boxes, where appearance is less critical, or for both inner and outer liners in applications where cost and sustainability are priorities.
Choosing Between Kraft and Test
Many corrugated boxes use a combination of the two liners: kraft on the outside for strength and presentation, and test on the inside for environmental efficiency and cost savings. For example, a double wall carton might feature a kraft outer liner with recycled test liners on the inside.
If you’re not quite sure what material to prioritise for your needs, check out our helpful table that summarises the benefits of each liner below:
| Feature | Kraft Liner (Virgin Fibre) | Test Liner (Recycled Fibre) |
| Strength & Durability | High strength, puncture resistant, excellent stacking | Good strength, suitable for everyday uses |
| Appearance | Smooth surface, consistent finish, premium look | Rougher texture, less consistent surface, visible “imperfections” |
| Moisture Resistance | More resistant to damp or humid conditions (but not waterproof) | Less resistant, better for dry storage/shipping |
| Environmental Impact | Made from virgin pulp (sustainably sourced forests), recyclable | Made from 100% recycled fibre, recyclable and highly eco-friendly |
| Cost | Higher – reflects premium strength and appearance | Lower – cost-effective, widely used in the industry |
| Common Applications | Export cartons, heavy-duty shipping, premium branded packaging | General packaging, e-commerce, everyday shipping |
Common Cardboard Box Styles (FEFCO Codes)
The corrugated packaging industry uses an internationally recognised set of design codes created by the European Federation of Corrugated Board Manufacturers (FEFCO). These codes provide a universal language for ordering boxes, ensuring consistency across suppliers and markets.
The most common styles we sell at Packn include:
- 0201: the most common type of shipping carton used worldwide. It features four flaps on the top and bottom of the box and must be sealed with packaging tape.
- 0426: a one-piece tuck-in lid carton. Open compared to a “pizza box” design, it has a hinged lid that folds over and tucks into the front, making it ideal for flat, shallow products and e-commerce fufillment.
- 0427: similar to the 0426, but with additional tuck-in slots along the front edge for a more secure closure. This makes it slightly stronger and more tamper-resistant, again popular in e-commerce and retail.
Beyond these 3 common styles, there are hundreds of FEFCO styles that cover everything from telescopic (2 interlocking) cartons to die-cut retail display. For most businesses, the 0201, 0426 and 0427 cover the vast majority of practical needs.
Understanding Box Strength & Weight Capacity
While fluting and wall type influence box strength, weight capacity is also a practical consideration for end users. The following ranges provide a rule of thumb:
- Single wall small box: 1-5kg
- Single wall medium box: 5-10kg
- Single wall large box: 10-15kg
- Double wall small box: 20-25kg
- Double wall medium box: 25 – 30kg
- Double wall large box: 30kg+
It is important to remember that performance varies with the box grade, the quality of materials, and how the goods are packed. Even a strong box can fail if the load is unevenly distributed or if inadequate sealing tape is used.
We always recommend using double wall boxes for removals, storage when shipping heavy goods.
Choosing the Right Box for Your Goods
Selecting the correct cardboard box comes down to four main considerations:
- Size: the box should fit your goods with enough space for protective filler, without excessive empty volume.
- Weight: heavier items require double wall construction for strength.
- Purpose: consider whether the box is for shipping, storage, removals, or retail presentation.
- Style:
- For general shipping and storage, the FEFCO 0201 standard carton remains the most widely used.
- For flat or shallow products (e.g. clothing, books, printed materials) or for e-commerce despatch, hinged-lid styles such as the 0426 and 0427 provide a secure, professional presentation and easy closure.
- For businesses that need fast assembly with glued bases, look to the 07xx series of crash-lock style boxes. We won’t cover this in depth here, but these are widely used in retail and subscription packaging due to their quick assembly.
Are Cardboard Boxes Eco-Friendly?
By choosing cardboard boxes, you’re already picking one of the most sustainable packaging materials available on the market. They are:
- 100% recyclable through standard UK recycling centres.
- Produced from a mix of virgin fibre (Kraft paper) and recycled fibre (Test liner) papers.
- Biodegradable, typically breaking down in less than three months in natural conditions.
- Renewable, as it is manufactured from wood pulp sourced from managed forests.
On average, corrugated boxes in the UK already contain more than 70% recycled content. The fibres can be recycled multiple times before they degrade beyond use, creating a closed-loop system that significantly reduced environmental impact compared to plastics or composites.
At Packn, we are committed to sourcing responsibly and providing packaging that supports both business efficiency and environmental responsibility. By choosing cardboard, you are not only protecting your goods but making a sustainable choice.
Final Thoughts
Cardboard boxes may simple at first glance, but they underpin the movement of goods across the world. By understanding the differences in material strength, fluting type, and box style, consumers can make more informed choices that reduce costs, improve product protection, and minimise environmental impact.
Whether you need lightweight single wall cartons for everyday e-commerce fulfilment or heavy-duty double wall boxes for industrial shipping, Packn provides a complete solution. With bulk discounts, UK-wide delivery, and a focus on sustainable materials, we ensure our customers receive packaging that is both practical and responsible.