The biggest factor in how often you should change your filter is the type of filter you use. There are two main filter types to choose from: fiberglass air filters and pleated air filters. Both types are disposable, but there are some important differences between them.

Fiberglass air filters are the more affordable of the two but less efficient at capturing dust and particles in the air. They generally need to be changed every 30 days or less.

Pleated air filters are more expensive at the outset, but they are also more efficient at trapping particles and can last up to 90 days, depending on use.

When you purchase a new air filter, you’ll find the manufacturer’s recommendations for the replacement schedule. This is a general guideline, and depending on the following factors, you may need to change it more often—or less often.

Tip: Some filter models offer a subscription service that delivers a new filter to your home on a regular schedule.