Royal Mail Parcel Size Guide 2026: Sizes, Weight Limits and Prices

Royal Mail parcel sizes decide what you pay before weight is even considered. A box that is 1cm too deep can move a parcel up a band, and that can add pounds to every order. For a business sending hundreds of parcels a month, that adds up quickly.

This guide covers every Royal Mail size band for 2026, the rules for tubes and international mail, the latest prices from the October 2026 tariff, and practical ways to keep your packaging inside the cheapest band.

Royal Mail Parcel Sizes at a Glance

Understanding the royal mail sizes for parcels helps businesses choose suitable packaging and avoid paying more than necessary for postage.

Royal Mail sorts UK mail into four main formats: Letter, Large Letter, Small Parcel and Medium Parcel. Anything bigger or heavier goes through Parcelforce Worldwide, which is part of Royal Mail Group.

Royal Mail's October 2026 online price guide confirms the Medium Parcel limit of 61cm long, 46cm wide and 46cm deep, with a 20kg weight limit. Its published guides also set the Small Parcel limit at 45cm by 35cm by 16cm and 2kg.

A parcel must meet all four limits for a band: length, width, depth and weight. If any one measurement goes over, the whole item moves up to the next band.

Because Royal Mail measures the finished parcel, the box you choose affects postage as much as the product does. Custom shipping boxes made to your product's measurements are one of the most reliable ways to stay inside the right band.

Royal Mail Small Parcel Size

The Small Parcel band covers most everyday eCommerce orders, including cosmetics, candles, books, accessories and small electronics.

The small parcel size royal mail allows is suitable for many compact products, provided the finished package stays within the following limits:

• Length: 45cm
• Width: 35cm
• Depth: 16cm
• Weight: 2kg

The 16cm depth is the limit most often missed. A box that fits the length and width easily but stands 17cm tall becomes a Medium Parcel, and on a 2nd Class stamp that moves the price from £4.60 to £7.50.

Royal Mail Medium Parcel Size

The Medium Parcel band is for bulkier or heavier items, such as shoes, small appliances, multi-item orders and wholesale samples.

If you're checking the medium size parcel royal mail accepts, the following measurements are the maximum permitted dimensions and weight.

Medium Parcel limits:

• Length: 61cm
• Width: 46cm
• Depth: 46cm
• Weight: 20kg

Unlike the Small Parcel band, Medium Parcels are priced in three weight steps: up to 2kg, up to 10kg and up to 20kg. Royal Mail has no "Large Parcel" band of its own. Anything over 61 × 46 × 46cm or 20kg needs Parcelforce Worldwide or another courier.

Checking the medium parcel royal mail size before ordering packaging can help prevent unnecessary postage charges, particularly when shipping bulky products.

Medium Parcels often carry heavier goods, so box strength matters as much as size. Corrugated shipping boxes are a common choice for orders in the 2kg to 20kg range, as the fluted board is built to handle the stacking and handling of parcel networks.

Letters and Large Letters

These formats are not parcels, but many small products fit them, and the savings are large.

• Letter: up to 24 × 16.5 × 0.5cm and 100g.
• Large Letter: up to 35.3 × 25 × 2.5cm and 750g.

A slim mailer that holds a T-shirt, a phone case or a flat cosmetic product can often go as a Large Letter. At Post Office prices from 5 October 2026, a 2nd Class Large Letter starts at £1.55 and a 2nd Class Small Parcel costs £4.60.

If you need tracking, buying online allows a heavier Large Letter. Tracked Large Letters bought online cost £2.90 for Tracked 48 and £3.90 for Tracked 24, and can weigh up to 1kg rather than 750g.

Tubes and Rolls

Posters, prints, plans and fabric samples are often sent in tubes. Royal Mail's guidance says the length of a cylindrical item plus twice its diameter must not exceed 104cm, and its longest dimension can be no more than 90cm.

Example: a tube 80cm long with a 10cm diameter measures 80 + (2 × 10) = 100cm, so it fits. The same tube at 12cm diameter measures 104cm, which is right on the limit. Leave yourself a small margin.

Royal Mail Parcel Sizes and Prices for 2026

Royal Mail changed its prices twice in 2026. Its Prices 2026 page lists a Post Office price guide and an online price guide, both effective from 5 October 2026, following the earlier April increase.

The October rise affected parcels rather than letters, with increases ranging from 25p on a Tracked 48 small parcel to £1.45 on a 1st Class medium parcel up to 20kg.

There are two price lists to know about:

• Post Office and stamp prices apply when you buy at the counter or use stamps.
• Online prices apply when you buy postage online, for example through Royal Mail Click & Drop.

Royal Mail Small Parcel Price (up to 2kg)

One point worth noticing: online, Tracked 48 is cheaper than an untracked 2nd Class parcel. For most online sellers, that makes it the default choice for small parcels.

If most of your orders fit the Small Parcel band, custom mailer boxes designed to stay within 45 × 35 × 16cm help you keep that lower price on every order.

For businesses comparing packaging options, knowing the medium parcel size royal mail permits can also help determine when an order needs a larger box and a different postage band.

Royal Mail Medium Parcel Price: 1st and 2nd Class

Royal Mail Medium Parcel Price: Tracked Services

VAT and Compensation

Royal Mail's price guide shows Tracked prices including VAT at 20%, while 1st and 2nd Class prices are exempt from VAT. VAT-registered businesses should check how this affects their reclaim. Tracked services bought online include compensation of up to £75.

Business account customers are on contract rates, which differ from the figures above. Royal Mail 24 and Royal Mail 48 account prices also rose on 5 October 2026, by 15p on a Royal Mail 48 parcel up to 2kg and 30p on Royal Mail 24.

Royal Mail Parcel Size Guide 2026 PDF

If you want the full tariff as a PDF, Royal Mail publishes official price guides on its Prices 2026 page (royalmail.com/prices2026). There is a Post Office version and an online version, and both include the size and weight guide. Use these official PDFs rather than third-party copies, because prices can change mid-year, as they did in October 2026.

Royal Mail Parcel Size Guide 2026: International

International rules are different from UK rules, so do not assume a box that works for UK delivery will work abroad.

For international parcels, Royal Mail limits the combined height, width and depth to 90cm, with no single side over 60cm and a 2kg weight limit. The October 2026 online guide notes that the Medium Parcel format is only available on International Tracked Heavier, for items up to 20kg.

Books and pamphlets can go up to 5kg if marked as "Printed Papers", and anything bigger or heavier can go through Parcelforce Worldwide. International prices depend on destination and weight, and parcels need a customs declaration, so check the price guide for the country you are sending to.

Larger Parcels: Parcelforce Worldwide

When a parcel is too big for a Medium Parcel, the Royal Mail Group option is Parcelforce Worldwide. Its standard UK services accept parcels up to 1.5m long, with length and girth combined up to 3m and a weight limit of 30kg. For bigger items, the express48large service takes parcels up to 2.5m long, or 5m in length and girth combined, still within 30kg per parcel.

Girth is the distance around the parcel at its widest point. Add the two shorter sides together and double the result.

Example: a box measuring 100 × 40 × 30cm has a girth of (40 + 30) × 2 = 140cm. Length and girth combined is 100 + 140 = 240cm, which is within the 3m limit.

Parcels this size and weight go through more handling, so the outer box needs to be strong. Custom printed corrugated boxes give you that strength while keeping your branding visible from collection to delivery.

How to Measure Your Parcel Correctly

Royal Mail measures the parcel as it is posted, not the product inside. That means the box, void fill, tape and labels all count.

1. Pack and seal first. Measure the finished parcel, not the empty box.
2. Measure the longest side. This is the length.
3. Measure the next longest side. This is the width.
4. Measure the shortest side. This is the depth or height. Check for bulging lids, overfilled mailers and taped flaps.
5. Weigh the packed parcel. Use accurate scales. A single wall box can add more weight than people expect.
6. Compare all four figures with the band limits. If any one is over, move up a band.

If you want a deeper explanation of how box dimensions are written and read, our guide to length, width and height in box measurements covers it in detail.

How Strict Is Royal Mail on Parcel Sizes?

Royal Mail does not publish a tolerance, so treat every limit as fixed. Underpaid or oversized items can lead to extra charges, and the person who pays depends on how the postage was bought.

For stamped mail, the recipient usually receives a grey "Fee to Pay" card. Royal Mail's fee schedule includes a £10 charge for any Medium Parcel that exceeds 61 × 46 × 46cm or 20kg, with packaging included in the measurement. Fees change from time to time, so check the current figures on Royal Mail's "pay a fee" page.

Businesses using account or platform labels can be charged directly. Shipping platforms that sell Royal Mail labels list correction charges of around £11 plus an admin fee per item for Tracked parcels over 610 × 460 × 460mm or the weight limit. Charges like these can cost more than the original postage, which is why accurate packaging matters.

How the Right Packaging Keeps Postage Down

Most postage overspend comes from packaging that is slightly the wrong size. A few changes make a real difference.

• Size the box to the band, not just the product. If your product is 30 × 20 × 12cm, a box with an external depth of 15cm keeps you inside the Small Parcel band. A stock box with a 20cm depth pushes the same order into Medium Parcel pricing.
• Use mailer boxes for Small Parcel orders. A mailer made to dimensions inside 45 × 35 × 16cm keeps orders in the cheaper band while still giving you branded presentation. Our article on mailer boxes for shipping, eCommerce and subscription services explains how brands use them.
• Choose stronger board for heavier Medium Parcels. Once orders reach several kilos, board strength matters more than a few millimetres. Corrugated board protects heavier contents without needing extra void fill.
• Reduce empty space. A tighter fit means less void fill, less weight and less movement in transit. It also lowers the chance of a bulging lid adding depth.
• Allow for board thickness. Internal and external sizes are not the same. Corrugated board adds thickness on every side, so always check the external dimensions against Royal Mail's limits.

If your current boxes regularly sit just over a band limit, packaging made to your product's exact measurements is often the simplest long-term fix.

Is It Cheaper to Send One Big Parcel or Several Smaller Ones?

It depends on total weight. Using October 2026 online prices:

The pattern is clear. When everything fits in a Small Parcel, keep it small. Once the order goes well beyond 2kg, a single Medium Parcel is usually cheaper than splitting, because the 10kg and 20kg weight steps are generous.

Sending one heavier parcel does put more strain on the box. Our guide to corrugated boxes for eCommerce and heavy shipping explains what to look for in packaging for heavier orders.

Ready to Fit Your Packaging to Royal Mail's Size Bands?

Custom Packaging Pro UK designs custom boxes around your product dimensions and the way you ship. If you want mailers or shipping boxes sized to stay within the Small or Medium Parcel bands, request a quote with your product sizes and order volumes.

Frequently Asked Questions

1. What are the Royal Mail parcel sizes?
   There are two Royal Mail parcel sizes for UK post. A Small Parcel can be up to 45 × 35 × 16cm and 2kg. A Medium Parcel can be up to 61 × 46 × 46cm and 20kg. Smaller flat items can go as a Letter (24 × 16.5 × 0.5cm, 100g) or Large Letter (35.3 × 25 × 2.5cm, 750g).
2. How strict is Royal Mail on parcel sizes?
   Very. There is no published tolerance, and Royal Mail measures the packed item including packaging. Oversized or underpaid items can result in a Fee to Pay for the recipient or a correction charge for business account senders.
3. How do I calculate my parcel size?
   Measure the sealed parcel. The longest side is the length, the next longest is the width and the shortest is the depth. Weigh it with all packaging included, then check every figure against the band limits.
4. How much does Royal Mail charge for a 2kg parcel?
   It depends on size and service. From 5 October 2026, a 2kg Small Parcel costs £3.75 by Tracked 48 online, £4.40 by 2nd Class online or £4.60 with a 2nd Class stamp. A 2kg Medium Parcel starts at £5.70 by Tracked 48 online.
5. Is it cheaper to send one big parcel or two smaller ones?
   If everything fits in one Small Parcel, that is cheapest. For orders well over 2kg, one Medium Parcel usually costs less than several Small Parcels because Medium Parcel prices cover up to 10kg and 20kg.
6. Is it cheaper to send multiple small packages or one large package?
   For heavier orders, one package is normally cheaper. For example, 8kg sent as one Medium Parcel by Tracked 48 online costs £7.55, compared with £15.00 for four separate 2kg Small Parcels.
7. What is the cheapest way to send a big package?
   Within Royal Mail's limits (61 × 46 × 46cm and 20kg), Tracked 48 bought online is the lowest-priced Medium Parcel option, at £12.25 up to 20kg. For anything larger, compare Parcelforce Worldwide with other UK couriers.
8. How do I send large parcels cheaply?
   Buy postage online rather than at the counter, use a box sized as closely to the product as possible, avoid unnecessary void fill and compare carriers for anything above 20kg. Regular senders can also ask Royal Mail about a business account.
9. How much does a 50 lb package cost to ship?
   A 50 lb package weighs about 22.7kg, which is over Royal Mail's 20kg Medium Parcel limit. It would need to go through Parcelforce Worldwide (up to 30kg) or another courier, and the price will depend on the service, size and destination.