• Size and weight: http://www.royalmail.com/personal/help-and-support/Tell-me-about-size-and-weight-formats
• Small parcel wide option: 45cm x 35cm x 8cm
• Small parcel deep option: 35cm x 25cm x 16cmm
• Prices: http://www.royalmail.com/personal/uk-delivery/2nd-class-mail
• Small Parcels: 0-1kg £2.80 - 1-2kg £3.80