HVAC Air Filter Replacement Calculator
Estimate how often to replace your HVAC air filter based on your home and living conditions. Includes guidance if you don’t know your filter size.
Result
Under typical conditions, replace your HVAC air filter every 60–90 days.
Use the inputs below to tailor this for pets, allergies, smoke, and HVAC runtime.
- Pets, smoke, and allergies usually shorten the interval.
- If the filter looks loaded early, replace sooner and use that as your new baseline.
Recommended replacements
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Inputs
What this calculator does
This calculator estimates how often you should replace your HVAC air filter based on household conditions.
When you should use it
- You want a replacement schedule without guessing
- Your home has pets, allergies, or heavy HVAC usage
- You don’t follow the manufacturer’s default timeline
How the estimate works
- Starts from common manufacturer guidance
- Adjusts frequency based on pets, occupants, and usage
- Outputs a recommended replacement interval
Assumptions & limits
- Assumes a standard residential HVAC system
- Does not account for unusual environmental conditions
- Results are estimates, not professional advice
FAQ
How often should I replace my HVAC air filter?
Most homes replace filters every 60–90 days, but pets, allergies, smoke, and heavy HVAC runtime can shorten that to 30–60 days. Use this calculator to tailor the interval to your situation.
Should I replace the filter earlier than the recommended date?
Yes. If airflow seems reduced, the filter looks visibly loaded, or dust builds up faster than usual, replace early and use that as your new baseline.
What if I don’t know my filter size?
You can still calculate a replacement interval without the size. When you’re able, check the numbers printed on the filter frame (like 16×25×1) or measure length × width × thickness in inches.
Do thicker (2–5 inch) filters last longer than 1-inch filters?
Often, yes. Thicker filters typically have more surface area and can last longer, but actual life still depends on airflow, dust, and household conditions. If performance drops early, replace sooner regardless of thickness.
Does a higher MERV rating mean I can wait longer to replace?
Not necessarily. Higher MERV filters may capture more particles, which can also make them load up faster in dusty or high-use homes. Replace based on the interval estimate and real-world signs like reduced airflow.
Built because someone forgot to replace their filter again. 🦆