HVAC Filter Size Guide

1. Find Your Filter Size

Enter your current filter dimensions or pick a common size:

Or select a common size: -- Select -- 14 x 20 x 1 14 x 25 x 1 16 x 20 x 1 16 x 25 x 1 20 x 20 x 1 20 x 25 x 1 20 x 25 x 4 20 x 30 x 1 24 x 24 x 1 25 x 25 x 1 16 x 25 x 4 20 x 20 x 4 Find Matching Filters

2. MERV Rating Comparison

MERV (Minimum Efficiency Reporting Value) rates a filter's ability to capture particles. Higher = better filtration but more airflow resistance.

3. Replacement Schedule Calculator

Answer these questions to get a personalized filter replacement schedule.

Filter depth 1 inch 2 inches 4 inches 5+ inches Pets in the home? Other factors: Location Suburban Urban (high pollution) Rural HVAC usage Normal (seasonal) Heavy (runs most of the year) Light (mild climate) Calculate Schedule

4. How to Measure Your Filter

1. Check the existing filter first. Most filters have the size printed on the frame (e.g., 20x25x1). This is the nominal size.
2. Actual vs. nominal size. The actual size is typically 0.25" to 0.5" smaller than the nominal size. Always buy by nominal size.
3. Measure the slot, not the filter. If no size is printed, measure the length, width, and depth of the filter slot in your HVAC unit.
4. Round up to the nearest inch. If your slot measures 19.5" x 24.5", the nominal size is 20x25.
5. Depth matters. 1" filters need frequent replacement. 4-5" filters last much longer and provide better filtration.
6. Direction arrow. Install with the arrow pointing toward the blower/furnace (toward airflow direction).