Royal Mail parcel sizes explained
Royal Mail charges by size first and weight second. Here are the four sizes, the exact limits, and how to keep your item in the cheapest one.
Letter
- Max size
- 24 × 16.5 × 0.5cm
- Max weight
- 100g
Good for: Birthday cards, standard letters, postcards
Starting prices: 1st Class Letter £1.80, 2nd Class Letter £0.91
Large Letter
- Max size
- 35.3 × 25 × 2.5cm
- Max weight
- 750g
Good for: A4 documents, CDs, slim paperbacks, magazines
Starting prices: 1st Class Large Letter £3.30, 2nd Class Large Letter £1.55
Small Parcel
- Max size
- 45 × 35 × 16cm
- Max weight
- 2kg
Good for: Shoeboxes, clothes, books, small electronics
Starting prices: 1st Class Small Parcel £5.90, 2nd Class Small Parcel £4.60, Tracked 24 (bought online) £4.80, Tracked 48 (bought online) £3.75
Medium Parcel
- Max size
- 61 × 46 × 46cm
- Max weight
- 20kg
Good for: Larger boxes, boots, small appliances, bundles
Starting prices: 1st Class Medium Parcel £8.70, 2nd Class Medium Parcel £7.50, Tracked 24 Medium (online) £8.65, Tracked 48 Medium (online) £7.60
How to measure your item
- Pack it first. Measure and weigh the finished parcel, including the box or bag, padding and label.
- Measure the three sides – length (longest side), width and depth (thickness) – in centimetres.
- Check thickness carefully. 5mm is the limit for a Letter and 2.5cm for a Large Letter. A simple trick: if it doesn't slide easily through a 2.5cm gap, it's a parcel.
- Weigh it on kitchen or parcel scales. Round up – a parcel that is 2.01kg is charged as over 2kg.
Other carriers' sizes
Couriers set their own limits. Evri accepts parcels up to 120cm long and 15kg; InPost lockers take parcels up to 64 × 41 × 38cm and 25kg. Because couriers mostly charge by weight, a light but bulky item is often much cheaper with them than with Royal Mail's Medium Parcel price. Compare prices with the calculator.