The Aprilaire 410 / 413 whole-house filter is labeled “16x25x4” but actually measures 16.52 x 29.38 x 4 inches. Unlike 1″ filters, 4″/5″/6″ whole-house filters don't share one universal nominal-to-actual conversion — always match by brand and model, not just the printed size.
From Aprilaire's own spec page. Fits 1410, 1610, 2410, 2416, 3410, 4400 cabinets. This is from the manufacturer's own spec sheet.
Match by brand + model, not nominal size. Confirm against your old filter or equipment manual before ordering.
Looking for a 1″ furnace filter instead? Use the full FilterKey tool.