Vent covers and registers come in many nominal sizes because HVAC openings vary by room, building age and installation type. The correct size is the one that matches your duct opening—not simply the most common size on the market.
Popular vent cover sizes
Find your measured opening below, then choose a cover made for its installation location:
| Opening size | Shop by size |
|---|---|
| 4×10 | Shop 4×10 |
| 4×12 | Shop 4×12 |
| 6×10 | Shop 6×10 |
| 6×12 | Shop 6×12 |
| 4×14 | Shop 4×14 |
| 8×10 | Shop 8×10 |
| 8×12 | Shop 8×12 |
| 10×10 | Shop 10×10 |
| 12×12 | Shop 12×12 |
| 14×14 | Shop 14×14 |
| 20×20 | Shop 20×20 |
| 20×30 | Shop 20×30 |
Size is only one part of the choice
A 12×12 floor opening and a 12×12 ceiling opening do not automatically use the same style of cover. Start with where the vent is installed, then match the opening size within that product category.
What does 4×10 mean?
A nominal 4×10 vent is designed for an opening that measures approximately 4 inches by 10 inches. The outside face of the cover is normally larger because it overlaps the opening.
Do not round the opening size
If your duct opening is unusual, do not assume a nearby common size will fit. Check both dimensions carefully and find the exact nominal size in the catalog.
If you have not measured yet, start with our How to Measure Vent Covers guide.