伊比利亚轨距，宽1668毫米，主要用于西班牙和葡萄牙的铁路。这是世界上使用中的第二宽的轨距，仅次于印度轨距。
西班牙和葡萄牙于1955年达成协议[1]，采用1668毫米伊比利亚轨距。19世纪期间，西班牙和葡萄牙采用不同的轨距。西班牙起初以1672毫米轨距兴建铁路，而葡萄牙起初以标准轨兴建铁路，后来改用1664毫米轨距，而两者轨距差异已经足够互通。[2]。
早期葡萄牙兴建的标准轨铁路后来改轨为伊比利亚轨距方便互通 - Assim, em 20 de Junho de 1860, funda a Companhia Real dos Caminhos de Ferro Portugueses que se propõe explorar as Linhas do Norte e do Leste e as linhas de que posteriormente obtivesse concessão. Thus, on June 20, 1860, founded the Society of Real Caminhos de Ferro Portugueses it proposes to exploit the lines of North and the East and the lines that subsequently obtain concession. De imediato a Companhia Real muda a bitola (1,44 metros) da linha já construída entre Lisboa e Asseca (68 Km.), passando-a para a bitola ibérica, com 1,67 metros, sem haver qualquer interrupção no serviço ferroviário. From immediate changes to the Company Real gauge (1.44 m) of the line already built between Lisbon and of Asseca (68 km), passing it to gauge the Iberian, with 1.67 metres, without any interruption in rail service. Archived copy. [2009-10-13]. （原始内容存档于2008-03-27）. [1] （页面存档备份，存于互联网档案馆）
