A variable-length table has a tabletop assembly which includes two leg mounting boards, two guide beams that interconnect the leg mounting boards, two connecting beam sets, two fixed tabletop units and a removable tabletop unit. Each connecting beam set includes two connecting beams disposed respectively on two sides of a corresponding one of the guide beams and mounted slidably thereto. Each fixed tabletop unit is mounted on a respective one of the connecting beams of each of the connecting beam sets. The removable tabletop unit includes a board member that is to be disposed removably between the fixed tabletop units when the fixed tabletop units are pulled apart so as to obtain a longer table length, and an opposite pair of flanges that are mounted foldably on the board member thereof and that cooperate with flanges of the fixed tabletop units so as to conceal the guide beams and the connecting beam sets when the longer table length is obtained. The removable tabletop unit can be concealed fully within a space formed between the leg mounting boards and the board member of the fixed tabletop units when the fixed tabletop units are pushed toward each other to obtain a shorter table length.