A practical guide to Royal Mail formats, tracking choices and parcel preparation.
Start with the parcel format
Royal Mail distinguishes letters, large letters, small parcels and medium parcels. Format depends on the outside measurements and packed weight together: a lightweight parcel can still be too large for a smaller format. Measure after taping the box, including any bulge.
The published UK size guide lists small parcels up to 45 × 35 × 16 cm and 2 kg, and medium parcels up to 61 × 46 × 46 cm and 20 kg. Those format limits are not a promise that every service accepts every parcel; check the particular service and current guide before paying.
| UK format | Outside dimensions | Maximum packed weight |
|---|---|---|
| Small parcel | 45 × 35 × 16 cm | 2 kg |
| Medium parcel | 61 × 46 × 46 cm | 20 kg |
Choose tracking deliberately
A proof-of-posting receipt and end-to-end tracking are different things. Review the selected service’s tracking, delivery-confirmation and signature features rather than assuming every Royal Mail product offers the same visibility. Keep the reference and receipt until the recipient confirms arrival.
Collection and posting-point options depend on the product and the way postage is bought. Check whether your chosen point accepts the label type, and whether a label must be printed before handover. A missed cut-off can change when an item enters the network.
Check contents before closing the box
Restrictions can apply to everyday items such as batteries, perfume, aerosols and liquids. Acceptance, packaging requirements and compensation exclusions are separate checks. An item being lawful to own does not mean it can travel in ordinary post.
For international goods, use the current destination guide and the customs information requested by the postal operator. A gift description must still identify what the item actually is. Do not apply a UK domestic format assumption to an international product.
A useful preparation example
A boxed jumper measuring 40 × 30 × 12 cm and weighing 1.4 kg is within the small-parcel format measurements listed above. If extra protection increases the depth to 18 cm, the same contents are no longer within that format. This is a measurement example, not a service quote.
SelectaParcel does not currently sell Royal Mail postage or retrieve Royal Mail tracking events. Follow the official source for current products, restrictions and buying options.
Questions worth clearing up
What if packaging takes the weight over a format limit?
Use the weight of the sealed parcel. If the contents weigh 1.9 kg but packaging brings the total to 2.1 kg, the packed result exceeds a 2 kg limit. Do not round it down to fit a format; check another suitable product and its full conditions.
Is proof of posting the same as full tracking?
No. Keep the receipt as handover evidence, but check the selected service’s actual tracking and delivery-confirmation features. The existence of a reference does not by itself establish every tracking or signature feature.
Can I apply the UK format table to overseas parcels?
Not automatically. International products and destinations can have different limits and requirements. Start from the current international product and country guide, then check contents and customs information for that route.
Primary sources & editorial review
Reviewed on 7 November 2026. Rules can change; check the specific product, destination and current official guidance before sending. This independent explanation is not a quote or a guarantee.
- Royal Mail — size and weight guide
- Royal Mail — how to weigh and measure a parcel
- HMRC — sending post or a parcel abroad
Spot something that needs updating? See our contact information and editorial approach.