A Guide to PiP Boxes & Letterbox Boxes

A guide to PiP boxes & letterbox boxes where we explain the different types and what they can be used for.



What are PiP Boxes?

PiP boxes are boxes that fit within the pricing in proportion (PiP) guidelines set out by Royal Mail. They help to control postage costs by falling within set PiP criteria. The 4 PiP sizes are; large letter (353 x 250 x 25mm), small parcel (450 x 350 x 160mm), medium parcel (610 x 460 x 460mm), and tubes.

Royal Mail created the PiP size range to help streamline their postal service. By setting a range of size limits it has made it easier for customers to estimate their shipping costs, while helping Royal Mail to process the parcels quickly and efficiently. PiP boxes are designed around these size limits so you know if you pack your online order in a large letter box you will get charged the large letter range, and so on for all the PiP sizes. There are also weight limits for each of the PiP sizes, the full criteria is below and more information is available on the Royal Mail site.


Royal Mail PiP Sizes

A table of the full Royal Mail PiP sizes including PiP tubes and typical items.


PiP DescriptionPiP Max SizePiP Max LengthPiP Max Width
PiP Max Depth
PiP Max WeightTypical Items
Letter240 x 165 x 5mm240mm (24cm)165mm (16.5cm)5mm (0.5cm)100g (0.1kg)Greetings cards, personal letters, postcards, bills
Large Letter353 x 250 x 25mm353mm (35.5cm)250mm (25cm)25mm (2.5cm)750g (0.75kg)A4 documents, certificates, magazines, CD or DVD in case, large greeting cards
Small Parcel450 x 350 x 160mm450mm (45cm)350mm (35cm)160mm (16cm)2000g (2kg)Shoes, portable speakers, mobile phones

Medium Parcel

610 x 460 x 460mm610mm (61cm)460mm (46cm)460mm (46cm)20kgGifts, shoes, heavy or bulky items
Large Parcel1.5 x 1.5 x 1.5m*1500mm (1.5m)*1500mm (1.5m)*
1500mm (1.5m)*
30kg
PiP Tubes900mm*900mm (90cm)1040mm (when 2 x dia + Length)**1040mm (when 2 x dia + Length)**
(various)**
Rolled posters, wall paper

* Large Parcel Sizes are a maximum of 3000mm (3m) with the length and depth combined.

** PiP Tubes can't be more than 1040mm when adding the length and two times the diameter. i.e. (120mm dia x 2) + 800mm length = 1040mm Max PiP Tube Size.



What are Large Letter Boxes?Letterbox Postal Box in PiP Large Letter Size

Large letter boxes are packaging boxes designed to fit through the Royal Mail large letter slot. The maximum size for a large letter box is 353mm x 250mm x 25mm. They are usually made from corrugated cardboard and help to control postage costs by shipping in a set size box.



What are Large Letter Postal Boxes used for?

Large letter postal boxes are used for sending small items through the Royal Mail postal system under the large letter size. Sending items in Royal Mail large letter boxes help to control your postal costs by keeping your parcels within the limits of the lower cost large letter size band. Large letter postal boxes are used by many different online stores who find them quick and easy to pack small online orders. If you are sending small online orders or samples, you could save money by using a large letter size box to keep your parcels under the large letter size limit of 353 mm x 250 mm x 25 mm.



Different Types of Large Letter Boxes

The different types of large letter boxes:

  • 0427 Pizza Box Style Large Letter Boxes: These are based on the 0427 box style with roll over sides to give extra crush resistance. These types of boxes look very professional and add a touch of class to your deliveries.

  • 0401 Style Large Letter Boxes: The satchel style has fold up sides but they don't roll over, instead they are locked in place by tabs on the lid. This style is good if you are having problems with the sides bulging and taking your parcels over the large letter size. The tabs lock in the sides stopping this happening.

  • Self-Seal Large Letter Boxes: Self-seal large letter boxes with a peel & seal strip are great for fast packaging of small orders. The self seal glue strip makes it quick and easy to seal and leave a clean and professional look to your large letter boxes.


Custom Large Letter Boxes

Custom large letter boxes personalised with your logo and brand pattern are a great opportunity to improve your brand image. We offer custom printing of your logo and brand messages on the inside or outside of our range of large letter boxes. We can also print a Royal Mail PPI stamp to make it easier to ship your large letter boxes.

Printed large letter boxes can be printed in various different ways:

  • Flexo printing is useful for high quantities and low costs, this is the most popular printing process for branding large letter boxes.

  • Litho Printing is a high quality printing process and offers full colour CMYK printing at photo quality printing.

  • Digital Printing is used for small volume printed large letter boxes. If you are looking for just a few hundred then this is the printing process we would use for you.



What are Letterbox Boxes?Flower Letterbox Box for Shipping Flowers in the Post

Letterbox boxes are cardboard boxes designed to fit through a standard letterbox. The most common letterbox slot size in the UK is around 254mm x 38mm (or 10 inches x 1.5 inches), so letterbox boxes are designed to fit within this maximum size. Keeping within this size helps to improve on-time delivery rates and reduce failed deliveries.

Letterbox postal boxes aim to solve the biggest problem that mail order companies have when trying to deliver on-time. When a customer is not in, a parcel often has a delay to the next day or even has to be picked up from the central Royal Mail depot. This could be very inconvenient for a customer who needs an online order urgently. So a postal box that is designed to fit through a letterbox significantly reduces the risk of failed deliveries, and in turn improves your on time delivery rates and customer satisfaction.


Different Types of Letterbox Boxes

There are different types of letterbox boxes that are best for different postal packaging applications. Here's a few of the most popular types:

  • 0427 Pizza Style Letterbox Boxes: The pizza box style is one of the most popular box styles for letterbox postal boxes. The roll over sides make them very strong while the tuck flap closure secures the lid, making sure it doesn't pop open in the post.

  • Letterbox Boxes with Internal Fittings: Letterbox boxes with internal fittings that are cut out to fit specific items are a great way to speed up packing. The cardboard fitting fits inside the postal box and the specific items slot neatly inside.

  • 0401 Style Letterbox Boxes: These are a maltese cross style of postal box which is a cost effective box designed to be quick and easy to pack. This design is great if you need to keep packaging costs low and packing speeds fast.

  • Self Seal Letterbox Boxes: Self seal letterbox boxes have a peel & seal strip that allows you to close the box with a strip of glue rather than tape.



What are Small Parcel Boxes?

Small parcel boxes are packaging boxes that fit within the Royal Mail small parcel size criteria. The maximum size for a small parcel box is 450mm x 350mm x 160mm and has a maximum weight of 2kg. Items of this sort of size are shoe boxes, portable speakers, boxed mobile phones, etc. Sending parcels that fit in the small parcel size limit will help you control your postal costs.


The different types of small parcel postal boxes

There are a few different types of small parcel postal boxes, some aimed at low cost packing, others aimed at giving a memorable unboxing experience for your customers with a professional look and feel to them. Here's some of the most popular types:

  • 0201 Standard Carton Small Parcel Boxes: The 0201 style of cardboard box is a low cost and very popular style for small parcel boxes. They have top and bottom flaps that can be taped closed, it's the most common design of cardboard box that you see around. These are a general purpose postal box that are great for sending a wide range of online orders via Royal Mail.

  • 0427 Pizza Style Small Parcel Boxes: The 0427 style that is often known as a pizza box style is another popular design for small parcel boxes. The hinged lid that opens like a presentation box coupled with the strong fold over sides gives these boxes and air of quality that is perfect for creating a memorable unboxing experience.

  • Self Seal Small Parcel Boxes: Self seal boxes have a peel & seal glue strip that is used to seal the box instead of using tape. This peel & seal closure strip makes boxes much faster to seal and gives a cleaner, more professional look to the parcel. Couple this with a quick and easy tear open strip and you make the unboxing experience frustration free and much more pleasant.


Medium Parcel Boxes

Medium parcel boxes are boxes that fit within the Royal Mail pricing in proportion Medium Parcel criteria. The maximum medium parcel size is 610mm x 460mm x 460mm with a maximum weight of 20kg. Typical items that are medium parcel size: large gifts & toys, household items like toasters & large speakers, or bulky items like big cushions.

Medium parcel boxes are usually a standard 0201 style box as this is the most cost effective carton for big boxes. They are mostly manufactured from a strong corrugated cardboard in either single wall or double wall. If your items are relatively light in weight (up to 5kg) then you can usually get away with using a general purpose single wall box. However, if your items are particularly delicate or more than 5kg you would be best to use a stronger double wall box that are better for heavier items. This is because heavier items get dropped and experience more damage than lighter items when in transit.

Flower Letterbox Box for sending online flowers

Letterbox Boxes

A range of letterbox sized boxes that can be used for posting online orders to ensure they fit through a letterbox.

Large Letter size boxes for sending small online orders.

Large Letter Boxes

Large letter boxes designed to fit the PiP large letter size to help you control your postage costs when sending online orders.

Small Parcel size PiP Boxes for sending small online orders.

Small Parcel Boxes

A range of small parcel boxes that fit within the small parcel PiP size criteria allowing you to ensure your parcels don't go over the size limit.

Medium Parcel size PiP Boxes for sending medium sized online orders

Medium Parcel Boxes

Medium Parcel boxes that fit under the Royal Mail medium parcel PiP size limits helping you to control your postage costs on online orders.