How often your family expects to use the heating system in their home will determine the answer. Consider changing your filter frequently if your family plans to leave the house during cold weather months. But if you do not often go outside, it may be possible to wait longer between changing your filter.
The average furnace filter will last approximately three months. Your furnace filter should be replaced every three months.
The manufacturer will also give you recommendations on when to change your filter. Manufacturers recommend changing your filter after each heating season. Other manufacturers suggest waiting until visible dirt builds up.