United Kingdom · Royal Mail
Royal Mail parcel size checker.
Measure your item, enter the weight, and see which Royal Mail format it is and whether it fits at all.
Quick answer: a Small Parcel is up to 45 × 35 × 16 cm and 2 kg. A Medium Parcel is up to 61 × 46 × 46 cm and 20 kg. Anything bigger is outside Royal Mail parcel limits.
Sources checked October 2026. Not affiliated with Royal Mail, Parcelforce, Evri, DPD or DHL.
Your parcel
Royal Mail format
Enter the size and weight, then press Check size.
Royal Mail UK size and weight limits
These are the UK limits printed in Royal Mail’s price guides valid from 5 October 2026. The checker picks the smallest format that fits both your measurements and your weight.
| Format | Maximum size | Maximum weight |
|---|---|---|
| Letter | 24 × 16.5 × 0.5 cm | 100 g |
| Large Letter | 35.3 × 25 × 2.5 cm | 750 g (1 kg for UK Tracked) |
| Small Parcel | 45 × 35 × 16 cm | 2 kg |
| Medium Parcel | 61 × 46 × 46 cm | 20 kg |
| Parcelforce Parcel | 1.5 m length, 3 m length and girth | 30 kg |
| Parcelforce Large Parcel | 2.5 m length, 4 m length and girth | 30 kg |
Small parcel: 1 kg or 2 kg?
Royal Mail’s October 2026 guides and its small parcel page give the UK Small Parcel weight limit as 2 kg. The only 1 kg limit in those guides is for a UK Tracked Large Letter (the standard Large Letter limit is 750 g). The same online guide still prints the older sum-of-sides rule (height + width + depth no more than 90 cm, no single side over 60 cm) for international small parcels, so you may see that rule quoted for other services.
How the checker measures
Royal Mail prints a length, width and depth for each format. The checker sorts your three measurements and compares the longest to the longest, so the order you type them does not matter. Measure the widest point of each side, including padding and any bulge, because Royal Mail applies the limit to the packed item.
Too big for a Medium Parcel?
Parcelforce Worldwide, part of the same price guide, takes parcels up to 1.5 m long and 3 m in length and girth (2.5 m and 4 m for large parcels), both up to 30 kg. This checker tells you when you are in that range but does not price it.
Sources
- Royal Mail: Our Prices, valid from 5 October 2026 (PDF) (retrieved October 2026)
- Royal Mail: Online Prices (Click & Drop), valid from 5 October 2026 (PDF) (retrieved October 2026)
- Royal Mail: Small parcel delivery (retrieved October 2026)
Frequently asked questions
What is the maximum size of a Royal Mail small parcel?
Up to 45 cm long, 35 cm wide and 16 cm deep, and up to 2 kg. Royal Mail states these as the maximum postage sizes it uses for small parcels.
What is the Royal Mail medium parcel size limit?
Up to 61 cm long, 46 cm wide and 46 cm deep, and up to 20 kg for UK services. For international sending, the October 2026 online guide says the medium parcel format is only available for International Tracked Heavier.
Is a Royal Mail small parcel 1 kg or 2 kg?
In the October 2026 guides it is 2 kg. A 1 kg limit appears only for a UK Tracked Large Letter, which is separate from a Small Parcel.
What if my item is small but heavy?
The weight limit applies as well as the size. A 40 × 30 × 10 cm item that weighs 3 kg is over the 2 kg Small Parcel limit, so it is priced as a Medium Parcel.
Does Royal Mail measure the box or the item?
The limits apply to the item as posted, so include the packaging. Measure the longest point in each direction.
A guide, not a quote
This page compares your measurements with limits the carriers publish. It does not query any carrier, cannot confirm acceptance or price, and collects no personal data. Carriers change limits and prices, so confirm with the carrier before you ship.