Flat Cardboard Box

• Extra flat postal box made of 100% recycled paper
• Especially suitable for shipping flat products
• Economical and versatile packaging solution

From: £0.52 Regular Price £0.55
In stock
Only %1 left
525 x 255 x 65 mm - brown/white - CLP01
* Request your bespoke size or request a quote for a larger quantity
Amount: 1 units
Free delivery over £100 *
Price per unit:
per unit
total: ex. VAT total: inc. VAT
  • Cut-off time 3 pm
  • Free delivery over £150 *
  • 30 Days Returns

* Please refer to our delivery policy page. For any queries please contact us.

Flat Cardboard Box Product Details

These large letter postal boxes are specially designed for delivery with the Royal Mail, with external dimensions that attract some of the cheapest postage rates available on the market. As they fit in standard domestic mail slots, both you and your customer save on delivery costs due to the parcel sizes.

With a sturdy design and tuck-in flaps on all sizes, you can be sure that the contents of your delivery will be kept safe and secure from bending and crushing. They are ideal for sending larger documents, books, items of clothing, catalogues and various other smaller and lighter objects.

Recommended for

  • These letter boxes are highly versatile, making them ideal for ecommerce and logistics. They are perfect for sending documents and relatively small and light objects that require some interior protective stuffing to ensure safe delivery.

Key Features


While these boxes are great value for money, they are also specially designed to reduce postage costs, representing a double saving for you and your customers. They are easily reusable for any returns, making the entire purchase process as streamlined as possible.

Suitable for letterboxes

The perfect size for delivery in standard mail slots in British houses, ensuring your items will be properly delivered through the door whether the customer is at home or not. This makes the delivery process as easy as possible for the customer and minimises lost parcels and all the paperwork this can create, saving you time and money.


These sturdy boxes are very versatile and are an ideal way to deliver documents and books, or small objects in a specifically sized and protective parcel. The fact they are boxes with corners (and not simply flat envelopes) offers a bit more protection from any rough treatment during delivery.


The boxes are completely recyclable and biodegradable, making them a green alternative to plastic pouches and bubble wrap and ensuring your customer knows you are an environmentally responsible company.

Are you interested in ordering larger quantities?

Please contact us via email at shop@dssmith.com.

How to measure a box?

When measuring a cardboard box, it is important to consider three key dimensions: length, width and height. These measurements provide the internal dimensions of the carton, allowing you to define the space available to pack products and ensure they fit properly.

The dimensions provided on our website are in Millimetres and are following the order LENGTH x WIDTH X HEIGHT.

To measure correctly a cardboard box follow these instructions:

1. Length: start by measuring the longest side of the box base

2. Width: rotate the box 90 degres and measured the other side of the box base

3. Height:measure the distance from the base to the top

What makes ePack sustainabile?

In today's society, sustainability has become a key focus. Consumers who are conscious about the environment are demanding eco-friendly packaging solutions. DS Smith ePack offers packaging solutions that are 100% eco-friendly, using fibres from responsible sources to combat deforestation. They use recycled or virgin paper from a certified chain of custody, and their corrugated cardboard packaging is both recyclable and biodegradable.

DS Smith ePack prioritizes sustainability by using responsible sources, recycled or virgin paper, and recyclable and biodegradable materials. Consumers consider sustainability as a crucial factor in their purchasing decisions, and non-sustainable packaging can lead to negative consequences for companies. Eco-friendly packaging not only benefits the environment but also improves brand image and reduces the carbon footprint.

What does FSC label means?

FSC (Forest Stewardship Council) labelled paper is an important choice for individuals and businesses looking to prioritize sustainability and responsible forest management. Using FSC labeled paper offers numerous benefits. It supports responsible forest management, reduces environmental impacts, promotes social responsibility, meets consumer demand for sustainable products, and ensures compliance with regulations and standards. By choosing FSC labeled paper, individuals and businesses can make a positive impact on the environment and contribute to a more sustainable future.

Postal Guide

One of the easiest ways to derive the maximum benefit from your deliveries is to use the postal option that is most closely tailored to your product and that aligns perfectly with the standards, dimensions and weights stipulated by the Royal Mail, ensuring you keep prices as low as possible for you and your customers and reducing difficulties with delays and damaged packages. This allows your business to keep the processing of orders and shipping as streamlined as possible, saving you time and money.

Letter Large letter Small parcel Medium parcel Large parcel
Maximum length 240 mm 353 mm 450 mm 610 mm > 610 mm
Maximum width 165 mm 250 mm 350 mm 460 mm > 460 mm
Maximum height 5 mm 25 mm 160 mm 460 mm > 460 mm
Maximum weight 100 g 750 g 2 kg 20 kg 30 kg

Epack offers a full range of Royal Mail-compliant envelopes and parcels for all your delivery needs, including two envelope types and three parcel types.

The letter and large letter envelopes can take weights of up to 750 grams, making them ideal for greeting cards, folded and unfolded letters, magazines and small objects such as DVDs or plastic cards. By using the standard Royal Mail dimensions, you ensure that your shipping costs as little as possible, is less likely to experience delays, and will fit standard mail slots in the UK, minimising delivery problems and the administrative burden of lost and damaged packages. The two different sizes allow you to tailor your packaging to the letter content, allowing you to minimise costs for simple document shipping with standard letters.

Royal Mail parcels come in three sizes – small, medium and large – and can accommodate items from 2 kg up to 30 kg. Whether your company specialises in clothing, electronics or games and entertainment, any potential product offered by your business will find the perfect parcel type to match and provide the necessary size and weight capacity to ensure smooth and safe delivery with adequate protective packaging.


Created by Heipifrom the Noun Project