Bag filter housings worldwide standardize on four bag sizes. Every Universal Filters bag — felt, mesh, welded, high-efficiency, oil-removal — is available in each, and if your housing is nonstandard, we cut to fit.
Standard Filter Bag Sizes
| Size | Diameter | Length | Surface area (approx.) | Typical max flow* | Bottom style |
|---|---|---|---|---|---|
| Size 1 | 7″ | 16.5″ | 2.2 ft² | ~90 GPM | Flat |
| Size 2 | 7″ | 32″ | 4.4 ft² | ~180 GPM | Flat |
| Size 3 | 4″ | 8″ | 0.5 ft² | ~25 GPM | Point |
| Size 4 | 4″ | 14″ | 1.0 ft² | ~45 GPM | Point |
*Clean water service; derate for viscosity, tight micron ratings, and heavy solids. See the sizing guide for how to size properly.
Which Size Do I Have?
Measure the bag, not the housing: diameter across the ring, length ring-to-bottom. Size 1 and 2 share the same 7″ ring, so a size 2 bag in a size 1 housing simply won’t fit the basket length — a common mix-up on reorders. Sizes 3 and 4 share the 4″ ring and have pointed bottoms.
Beyond the Standard Four
We also build the less-common standards — size 5 (4″×24″), sizes 7/8/9 (5.65″ diameter × 15″/20″/32″, the Rosedale model 6 sizes), and the fast-growing size 12 (8″×32″) — plus fully custom diameters and lengths for OEM and specialty housings, and tie-on styles that need no housing at all. If you can measure it, we can make it.
📄 Download the Filter Bag Sizes & Dimensions spec sheet (PDF)
Reordering? The fastest path is the part number stamped on your current bag — call 800-554-8555 or send it through the quote form.