Depending on how much you use it, a treadmill’s belt will have different shelf life. Some expect the belt to last five years, while others think it is all about their maintenance schedule.
How long a belt will last depends on how much it gets used (hours of use), how often it’s lubed and how much the person weigh. If you’re a light user, expect the belt to last as many as eight years while a heavier user or someone that doesn’t lube might find themselves replacing it in two years. It all comes down to maintenance.