
Very few people have complained about buying a cord or cable that was too long, but lots of people have quickly regretted buying one that is too short -- even by half an inch.
When ordering cords or cables, always get a bit more than you think you need. The cost for the longer cord or cable is tiny compared to the cost in time and money of returning the short one and delaying your installation, or busting down walls and rearranging equipment to make the short cable work.