Find My Filter Find My Filter Step 1 of 3 What size filter does your home use? Enter the size printed on your current filter, or use the quick guide below. I Know My Size Type in the three numbers from your filter. Help Me Find It Show me where to look. Filter size in inches Width - + Height - + Depth - + Width and height can be entered in either order. Depth is usually 1, 2, 4, or 5. Not sure of your size? Here is how to find it. Check the old filter. The size is usually printed on the cardboard frame, like 20x25x1. Those three numbers are width, height, and depth in inches. Measure the slot. If the old filter is gone, measure the opening it sits in: across, top to bottom, and how deep the slot is. Common sizes. Tap one to fill the form: 20 x 25 x 1 16 x 25 x 1 20 x 20 x 1 16 x 20 x 1 14 x 20 x 1 20 x 30 x 1 24 x 24 x 1 16 x 24 x 1 Continue