mail sizes

defined by royal mail postal formats

Our Handling Charges,  and your forwarding options,  are based upon the very precise size and weight limits below.


a letter is... a letter!

To be classed as a Letter, an item must be under 100gm in weight,  no larger than 24 x 16.5cm and less than 5mm in thickness.

UK letter size
when is it a large letter?

The next step up,  with a maximum size of 35.3 x 25cm and up to 2.5cm,  or 1 inch,  thick is the Large Letter format.

A Large Letter can weigh as much as 750gm and might contain things like A4 documents,  cased DVDs or magazines.

UK large letter size mail by expost
is this a parcel?

The Small Parcel format,  weighing up to 2Kg and with a maximum size of 45 x 35 x 16cm,  can be carried by standard Royal Mail post,  just like the two letter formats.

You can,  however,  use your mailbox for items up to 20Kg in weight and as large as 61 x 46 x 46cm  (the Royal Mail's Medium Parcel limits) at no extra charge. . .   but they must be forwarded by courier.

British Mailbox parcel size and weight limit for forwarding