Calculator
HVAC Filter Calculator
“Every 90 days” is a starting point, not a rule for every household. This calculator adjusts that baseline for pets, allergies or dust, and filter thickness, then gives you a real replacements-per-year number.
Published
- Replacement interval
- about 90 days
- Replacements per year
- about 4.1
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How we calculate this
- Baseline interval
- ENERGY STAR's own guidance: check monthly, and change "at a minimum" every 90 days (3 months) for a standard filter with no pets or allergies in the home. ENERGY STAR, "Heat & Cool Efficiently".
- Pets, allergies/dust, and filter thickness adjustments
- These three inputs shorten or extend the baseline — pets and allergies/dust each cut it by roughly a third, and a thicker filter roughly doubles it. Every HVAC source agrees on the direction of each of these, but none ties a precise multiplier to a published study, so treat these three adjustments as reasonable estimates, not sourced facts the way the 3-month baseline is.
Frequently asked questions
- Why are the pet/allergy/thickness adjustments estimates instead of sourced?
- Every HVAC and manufacturer source agrees pets, allergies, and dust shorten the standard interval, and a thicker filter extends it — but none of them ties a specific multiplier to a study we could cite, unlike the 3-month ENERGY STAR baseline itself. The adjustments here are reasonable, clearly labeled estimates, not a claim of precision.
- What if I have both pets and allergies in the home?
- Both adjustments apply together, shortening the interval further — select "yes" on both and the calculator combines them.
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