The Minimum Efficiency Reporting Value (MERV) scale (1–16) measures how well a filter captures particles. What is a MERV rating? | US EPA

Residential filters are typically 1 inch thick, but high-efficiency systems may use 4- or 5-inch filters. 2. Choose the Right MERV Rating

When buying central air conditioning filters, you must balance air filtration quality with your system's airflow requirements to avoid equipment damage. 1. Find Your Filter Size

Look for the "nominal size" (e.g., 20x25x1) printed on the edge of your current filter.