To find your air filter size, look at the side of the existing filter — it will be printed in inches (e.g., 16x25x1 or 20x20x4). If there’s no label, measure the filter slot opening — width × height × depth. Most homes use 1-inch standard filters in furnace cabinets; larger 4-inch or 5-inch media filters live in dedicated filter housings.

How to identify the size

  • Check the printed size on the side of the current filter
  • If unlabeled, measure W × H × Depth in inches
  • Common sizes: 16x20x1, 16x25x1, 20x25x1, 20x25x4, 20x25x5
  • Round nominal to printed size (filters are often slightly smaller than the slot)

We confirm the right size and MERV during every AC tune-up or furnace tune-up.