Filter King Merv 8 19x20x1 6-Pack Air Filter actual size is 19x20x.75. Our 19x20x1 Furnace Filters are designed to last up to 90 days. These pleated 1-inch air filters are ideal for maintaining the efficiency of your heating and cooling systems. Make sure you measure your filter. The actual size of this pleated Merv 8 filter is 19 x 20 x 3/4