When it comes to changing furnace filters, there are several factors to take into consideration. Here are some things to think about before it's time for your next swap. Filter Variety Disposable fiberglass panel or electrostatic panel filters need to be changed every one to three months. Higher-quality pleated filters last anywhere from three to six months, while high-efficiency particulate air (HEPA) filters, which meet certain efficiency standards set by the United States Department of Energy, last many months. Allergy Status A cleaner filter helps alleviate allergy symptoms through the removal of more dust, pollen, bacteria and mold than an older, dirtier filter. If you or your family members struggle with allergies, change your filter every 20 to 45 days. Number of Pets Pet dander is also more efficiently removed from the air when your furnace filter is cleaner. The more pets you have, the more frequently you need to prioritize changing your furnace filter. A clean filter improves the air quality flowing through your home. If you have a single pet, your filter needs to be replaced at least once every 60 days. However, if you have multiple pets, plan to replace your filter at least once a month. Home Use Vacation homes that aren't rented out on a nightly basis receive far less use, so the furnace filter probably only needs to be changed once every 6 to 12 months. If you live alone and don't have any pets, changing a furnace filter is probably not needed as often as in full households. Let the filter be the guide, and always change the filter when it appears dirty. Presence of a Filter Gauge The indicator needle on the gauge tells you when it's time to change a furnace filter. It senses the air pressure between the filter and the blower. If your HVAC system is equipped with this component, watch it carefully and know when to replace the filter.