Large letter royal mail size

According to the Royal Mail's size and weight guidelines, a "Large Letter" is defined as a parcel that meets the following dimensions:

These dimensions are based on the maximum size of a parcel that can be sent as a large letter, rather than a parcel. If your parcel exceeds these dimensions, it will be classified as a parcel and will require a parcel delivery service.

It's worth noting that even if your parcel meets the dimensions for a large letter, it may still be subject to additional charges or restrictions if it weighs more than 750g (1.65 lbs) or contains certain types of items, such as lithium batteries or hazardous materials.