The ideal percentage at which to replace your filter largely depends on your personal comfort level. Changing your filter before it's fully used up can enhance the airflow in your HVAC system, reduce energy consumption, and improve overall filter efficiency. At Woosh, we strive to balance these benefits with the cost implications of switching to a new filter. Many of our users opt to replace their filters when about 20% of filter life remains, while others wait until the filter reaches 0%. We recommend monitoring your filter's performance and making a replacement decision that best aligns with your comfort and preferences.