The answer to 'how long does air filter last' is that the lifespan of an air filter can vary, but most need to be replaced every 1-3 months. The exact duration depends on factors like the type of filter, the size of your home, how many people live there, and how much the HVAC system is used.
Disposable fiberglass filters are the most affordable but only last 30-60 days on average. Pleated filters, which capture more particles, typically need to be changed every 90 days. Permanent or reusable filters can last 6-12 months with proper cleaning, but they require more maintenance. It's a good idea to check your filter monthly and replace it when it looks dirty or clogged.