16x25x4 furnace filter
Sizes, MERV guidance and a replacement schedule for 4-inch 16x25x4 air filters.
When to replace
Carrier: thicker 3- to 5-inch media filters can typically last six to nine months (a 4-inch filter around six months), depending on use. Pets, allergies, construction dust and heavy heating/cooling use all shorten the interval.
Choosing a MERV rating
MERV (Minimum Efficiency Reporting Value) reports a filter's ability to capture particles between 0.3 and 10 microns; higher MERV traps more of specific particle sizes. EPA: if upgrading, choose at least MERV 13 or as high as your system fan and filter slot can accommodate; you may need an HVAC technician to confirm.
| Rating | Average capture efficiency (EPA) |
|---|---|
| MERV 1-4 | 3.0-10.0 µm: less than 20% |
| MERV 5 | 3.0-10.0 µm: ≥20% |
| MERV 6 | 3.0-10.0 µm: ≥35% |
| MERV 7 | 3.0-10.0 µm: ≥50% |
Table excerpt; see EPA for MERV 8-16.
FAQ
What is the actual size of a 16x25x4 filter?
Nominal 16x25x4 filters are slightly smaller than the label so they slide in; FilterBuy lists this size at 15.5 x 24.5 x 3.63 inches. Exact dimensions vary a little by brand.
How often should I change a 16x25x4 filter?
Carrier: thicker 3- to 5-inch media filters can typically last six to nine months (a 4-inch filter around six months), depending on use. Follow your HVAC manufacturer's recommendation.
Which MERV rating should I buy?
MERV (Minimum Efficiency Reporting Value) reports a filter's ability to capture particles between 0.3 and 10 microns; higher MERV traps more of specific particle sizes. EPA: if upgrading, choose at least MERV 13 or as high as your system fan and filter slot can accommodate; you may need an HVAC technician to confirm.
Sources
- https://filterbuy.com/air-filters/16x25x4/
- https://www.carrier.com/us/en/residential/hvac-resources/furnaces/changing-furnace-filters/
- https://www.epa.gov/indoor-air-quality-iaq/what-merv-rating
Data checked 2026-10-17. Always confirm the part number printed on your current filter or in your owner's manual.