A cable tie has a buckle member, an engaging band, and an insertion band. The buckle member has an engaging hole and an engaging block. The engaging block is resilient, is formed in the buckle member, and extends into the engaging hole. The engaging band is selectively inserted into the engaging hole and has two side faces and a thickness. At least one of the side faces has a channel having multiple unidirectional teeth. The insertion band is integrally formed on and extends from the buckle member and has a thickness. The insertion band is stacked with the engaging band when the insertion band and the engaging band are inserted into the engaging hole in the buckle member. The sum of the thicknesses of the insertion band and the engaging band is substantially equal to the height of the engaging hole.