The invention relates to a cargo surface for a truck or a trailer which is intended for being retrofitted to a chassis (4) of the truck or trailer subsequent to the truck or trailer having been manufactured and delivered from the manufacturing site of the truck or trailer. The cargo surface comprises at least two individual surface units (10). Each of the cargo surface units (10) has a modular predefined length (L) being independent of the brand and type of truck or trailer onto which the cargo surface is to be retrofitted. The number of modular cargo surface units (10) to be retrofitted to the truck or trailer is determined by the length of what is to constitute the cargo surface of the truck or trailer. The number of modular, predefined length cargo surface units (10) to be retrofitted to the truck or trailer is furthermore determined by the brand and the type of truck or trailer.