If your business relies on Royal Mail for distribution, then familiarity with the postal size guide is key to maximising your P&P profits.

Sending out packages larger than necessary could easily cost a big business thousands of pounds a year – so check out the guide below, then view our range of large letter and small parcel packaging solutions for more cost-efficient deliveries.

Royal Mail size and weight guide (UK)


Max weight – 100g
Max length – 24cm
Max width – 16.5cm
Max depth – 5mm

Large Letter

Max weight – 750g
Max length – 35.3cm
Max width – 25cm
Max depth – 2.5cm

Small Parcel

Max weight – 2kg
Max length – 45cm
Max width – 35cm
Max depth – 16cm

Medium Parcel

Max weight – 20kg
Max length – 61cm
Max width – 46cm
Max depth – 46cm

Large parcel

Max weight – 30kg
Max length – 1.5m (max 3m length and depth combined)

Postal tubes

Max size – Length of the item plus 2 x diameter must be less than 104cm. Longest dimension max 90cm.

Royal Mail size and weight guide (International)

If you ship outside of the UK, the size and weight restrictions of letters and large letters remain the same.

Internationally though, all parcels must measure no more than 90cm (length, width and depth combined) with no single side longer than 60cm.

For advice on efficient posting and packaging solutions, just give us a call on 020 8801 8144 or contact your local depot.


We have a comprehensive range of products;
for further details and to find the best solution for your packaging needs,
please contact our sales team.