If you’re sending packages within the UK, understanding Royal Mail’s parcel size categories is one of the smartest things you can do. Whether you’re shipping a birthday gift, returning an online purchase, or posting customer orders for your business, knowing which parcel type to choose can help you save money and avoid delivery issues. In this guide, you’ll find all the essential details on Royal Mail parcel sizes, label requirements, weight limits, and postage costs for 2025.

What is Considered a Large Letter by Royal Mail?

A large letter is designed for items that are bigger than a standard letter but still relatively flat. This size is perfect for sending paperwork, magazines, thin books, and other documents that won’t fit in a standard envelope. According to Royal Mail’s size guide, a large letter can be up to 35.3 cm in length, 25 cm in width, and no thicker than 2.5 cm. The maximum weight allowed for this category is 750 grams. Anything beyond these measurements would need to be sent as a parcel.

What Counts as a Small Parcel?

A small parcel is the next step up from a large letter and is one of the most commonly used parcel sizes. It’s ideal for sending bulkier items that don’t weigh too much. Commonly posted items in this category include clothing, small tech items, books, and boxed products. A small parcel must not exceed 45 cm in length, 35 cm in width, and 16 cm in depth. The weight limit for this size is 2 kilograms. If your parcel fits within these measurements, you’ll be able to take advantage of the lower postage rates assigned to this category.

What is the Maximum Size for Royal Mail Parcels?

While Royal Mail handles a wide range of parcel sizes, there is a maximum limit to what they will accept. If your parcel is any larger, you’ll need to use a courier service instead. The maximum allowed size for a Royal Mail parcel is 61 cm in length, 46 cm in width, and 46 cm in depth. The heaviest parcel Royal Mail will accept weighs 20 kilograms. These limits ensure that all parcels can be handled safely and efficiently during the delivery process.

How Are Royal Mail Parcel Sizes Categorised?

Royal Mail parcels are split into four main size categories. These include large letters, small parcels, medium parcels, and large parcels. The large letter and small parcel categories have already been explained, but medium parcels follow the same maximum dimensions as the overall Royal Mail limit: 61 cm by 46 cm by 46 cm, with a 20-kilogram weight cap. Anything above this size or weight would be classed as a large parcel and handled by an alternative delivery service, often at a higher cost. Understanding these categories makes it easier to select the right option and helps you avoid overpaying or running into size issues at the Post Office.

What Size Are Royal Mail Shipping Labels?

When printing a Royal Mail shipping label, it’s useful to know the standard size so you can prepare your packaging accordingly. Most parcel labels are around 10 cm by 15 cm. These labels include essential information like the delivery and return address, tracking barcode, and postage details. It’s important to place the label on a flat, visible part of the parcel to ensure it can be scanned and read without any problems. A well-positioned and clearly printed label can help prevent delays, especially when using tracked or signed-for services.

How Should You Measure Your Parcel for Royal Mail?

Measuring your parcel properly can save you from unexpected costs or delays. To do this, take a ruler or measuring tape and check the length, width, and height of the parcel. The length is always the longest side, followed by the width and then the height. You’ll need to measure in centimetres, as Royal Mail’s size guides are based on metric dimensions. Make sure to compare your parcel’s size to the allowed dimensions for its category before choosing a postage type.

What is the Maximum Weight Allowed for a Royal Mail Parcel?

Royal Mail allows parcels up to a maximum weight of 20 kilograms. This weight limit applies across small, medium, and large parcel categories. Any parcel heavier than 20 kilograms will need to be sent via a specialist courier. Staying within the weight limit helps ensure your parcel is accepted, processed, and delivered without complications.

How Much Does It Cost to Send a Parcel via Royal Mail in 2025?

Service Type	Parcel Size	Online Price	Post Office Price
1st Class (Next-Day Aim)	Small Parcel (up to 2kg)	£4.19	£4.99
	Medium Parcel (up to 20kg)	£5.85	£7.19
2nd Class (2–3 Days Aim)	Small Parcel (up to 2kg)	£3.35	£3.90
	Medium Parcel (up to 20kg)	£4.95	£6.29
Tracked 24 (Next-Day Aim)	–	from £4.29	–
Tracked 48 (2–3 Days Aim)	–	from £3.45	–

Are There Any Restrictions on What I Can Send with Royal Mail?

Yes, there are restrictions on certain items that cannot be sent through Royal Mail. Prohibited items include explosives, flammable substances, and hazardous materials. There are also restrictions on sending certain items internationally, such as alcohol, tobacco, and perishable goods. It’s important to check Royal Mail’s list of prohibited and restricted items before sending your parcel to avoid any issues.

Can You Add Tracking for Business Parcels?

Tracking is a valuable tool for businesses that send parcels regularly. It adds a layer of protection for both the sender and the recipient by providing updates on the parcel’s location throughout its journey. Royal Mail’s Tracked 24 and Tracked 48 services include tracking as standard. If you run an online store, you can also integrate Royal Mail tracking with platforms like Shopify, Etsy, or eBay, giving customers peace of mind while reducing customer service queries.

Why Its Important to have the Correct Sizes

Knowing the correct Royal Mail parcel size before you post something can save you money, reduce errors, and make the entire delivery process smoother. From large letters to tracked services, Royal Mail offers a range of options that suit individuals and businesses alike. By measuring your items carefully, understanding the parcel categories, and checking current rates, you’ll always be prepared to send with confidence.

If you’re unsure about costs, the Royal Mail website features a helpful postage calculator that gives you real-time price estimates based on your parcel’s size, weight, and destination.

Shipping Warning Labels For Approved Boxes

Shipping warning labels play an important role in further protecting Royal Mail approved boxes during transit. These labels provide clear instructions on how parcels should be handled, reducing the risk of damage or mishandling. For example, labels like “Fragile” or “Handle with Care” indicate that the contents require special attention, while “This Way Up” ensures the parcel is kept in the correct orientation.

By applying these labels to your Royal Mail-approved boxes, you not only help ensure the safety of your items but also make it easier for postal workers and couriers to identify and respond to any special requirements. Properly labelled boxes are less likely to be dropped, stacked incorrectly, or exposed to unnecessary stress, ultimately leading to a smoother delivery process and a better customer experience.

How to Add Royal Mail Tracking for Business Parcels

Adding tracking to your Royal Mail parcels can provide peace of mind for both you and your customers. Tracking allows you to monitor the progress of your shipments and ensures that parcels reach their destination securely. Here’s a comprehensive guide on how to add Royal Mail tracking to your business parcels.

To start using Royal Mail’s tracking services, you’ll need to set up a business account. This account provides access to various shipping options, including tracking, bulk mailing, and discounted rates.

Visit the Royal Mail Website: Go to the Royal Mail business section.
Register for an Account: Fill out the registration form with your business details.
Choose a Service Plan: Select a service plan that fits your business needs. Royal Mail offers different plans based on the volume of mail and parcels you send.

Royal Mail offers several tracked services for business parcels. Choose the service that best meets your requirements:
- Tracked 24: Aims to deliver parcels within 24 hours, with full tracking and signature on delivery.
- Tracked 48: Aims to deliver parcels within 48 hours, with full tracking and signature on delivery.
- Special Delivery Guaranteed by 1pm: Ensures delivery by 1pm the next working day, with tracking and signature on delivery.
- International Tracked & Signed: Provides tracking and a signature on delivery for international parcels.

Using Royal Mail’s online tools, you can print shipping labels that include tracking information.

Log In to Your Business Account: Access your Royal Mail business account online.
Create a Shipment: Enter the parcel details, including the recipient’s address and the parcel’s weight and dimensions.
Select a Tracked Service: Choose the appropriate tracked service from the available options.
Print the Label: Generate and print the shipping label, which will include the tracking number and barcode.

Ensure the shipping label is securely attached to your parcel. The label should be placed on the largest flat surface of the parcel, ensuring the barcode is clear and visible for scanning.

Royal Mail offers collection services for business customers, or you can drop off parcels at a nearby post office or Royal Mail collection point.
- Schedule a Collection: Arrange for Royal Mail to collect parcels from your business location.
- Drop Off at a Post Office: Take your parcels to a post office or Royal Mail drop-off point.

Once your parcels are shipped, you and your customers can track their progress using the tracking number provided.

Royal Mail Website or App: Enter the tracking number on the Royal Mail website or app to monitor the status of the parcel.
Automated Notifications: Set up automated notifications to keep your customers informed about their parcel’s status.

Understanding Royal Mail’s parcel sizes and guidelines helps ensure your packages are sent correctly and efficiently. From large letters to medium parcels, knowing the dimensions and weight limits can save you time and prevent potential issues with your shipments. Whether you’re sending documents, gifts, or products, Royal Mail has a range of options to suit your needs.

Make sure to check their website for the most current information and pricing to guarantee a smooth shipping experience.

By familiarising yourself with the different parcel categories, label requirements, and common queries, you can optimise your shipping process and avoid common pitfalls.

Whether you’re a business owner or an individual sender, having this knowledge at your fingertips can make a significant difference in your mailing experience. So, the next time you ask, “What size is a large letter Royal Mail?” or “What size is a medium parcel Royal Mail?” you’ll have the answers ready to ensure your parcels are correctly categorised and efficiently delivered.

Need Royal Mail Approved Boxes? Hub Packaging Can Help

If you’re sending small parcels, large letters, or tracked business orders, having the right packaging makes a big difference. At Hub Packaging, we supply Royal Mail approved boxes that meet official size and weight guidelines—perfect for eCommerce businesses, online sellers, or anyone posting regularly.

We offer strong, secure, and cost-effective packaging solutions designed to protect your parcels and keep your posting process hassle-free.

📦 Get in touch today to find out how we can support your business:

📧 Email: sales@hub-packaging.com

Sales: +4428 4175 4977

Sales: +3531 866 0136