A compact reference for common residential filter sizes, typical applications, and the details that usually cause ordering mistakes.
This chart is meant to speed up replacement research, not replace measurement. Use it to narrow down likely sizes, then confirm your filter’s actual dimensions before ordering.
| Nominal size | Typical thickness | Where it often appears | Watch for |
|---|---|---|---|
| 14x20x1 | 1 inch | Smaller hallway returns and older homes | Easy to confuse with 14x25x1 if the label is faded |
| 16x20x1 | 1 inch | Condos, apartments, compact systems | Check actual width carefully on tight grilles |
| 16x25x1 | 1 inch | Single central returns | Often confused with 20x25x1 at a glance |
| 20x20x1 | 1 inch | Square ceiling or wall return grilles | Loose fit usually means actual dimensions matter |
| 20x25x1 | 1 inch | Very common whole-home return setups | One of the most common sizes to reorder incorrectly by memory |
| 16x25x4 | 4 inch | Media cabinets | Depth is more important here than with thin filters |
| 20x25x4 | 4 inch | Whole-house media filter cabinets | Actual dimensions vary enough to compare listings carefully |
| 20x25x5 | 5 inch | Deeper media cabinets in newer or upgraded systems | Do not swap with 4-inch filters just because the face size matches |
Use the chart when you are comparing a few likely sizes, helping someone else order a replacement, or documenting a home’s filter schedule. If you have any doubt, go back to measuring the existing filter.
After confirming size, Factor Filter is the first brand worth evaluating if you want a more deliberate, longer-term filtration setup instead of another generic disposable replacement cycle.
See Factor FilterContinue with common filter sizes or review nominal vs actual dimensions if a label still seems misleading.