3x10 Metal Floor Vents: Free Area, Airflow and Duct Fit
A 3x10 floor vent has a free area of 13.2 square inches and a calculated airflow of 46 CFM, and it drops into a duct opening of 72 x 250 mm.
- Duct opening
- 2.83″ × 9.84″
- Metric
- 72 × 250 mm
- Best free area
- 13.2 sq in
- Comes in
- Drop-In · Upgraded 2-in-1 · Undermount
3x10 is the narrow floor size fed by 3-inch branch ducts in bedrooms and hallways, and at 13.2 square inches it carries more free area than its 30 square inches of nominal face would suggest, because the slot runs the full perimeter of the opening rather than across a louvred face.
Free area and airflow at this size
| Product | Free area | Open | Airflow | Price | |
|---|---|---|---|---|---|
| Drop-In Floor Vent [Metal] | 13.2 sq in | 44% | ≈ 46 CFM | from $30.59 | View 3x10 |
| Upgraded 2-in-1 Drop In Vent with Insert | 13.2 sq in | 44% | ≈ 46 CFM | from $37.99 | View 3x10 |
| Undermount Flush Floor Vent [Metal] | 12.2 sq in | 41% | ≈ 42 CFM | from $54.99 | View 3x10 |
Free area is the open cross-section air actually passes through, not the outside of the cover. How we calculate it.
Measuring for this size
The two floor products want slightly different holes at this size, 72.0 mm by 250.0 mm for the Drop-In and 73.9 mm by 251.9 mm for the Undermount, so measure the opening before choosing.
Is a 3x10 floor vent the same part as a 3x10 wall vent?
No. Floor vents are built to be walked on and wall vents are not, and the floor versions carry more free area: 13.2 square inches on the Drop-In and 12.2 on the Undermount, against 10.3 on the 3x10 wall vent. They also take different duct openings, so the two are not interchangeable even though the size label matches.
Will a 3x10 vent cover a slightly larger hole?
Usually, within reason. The cover is built larger than the duct opening so its flange has something to bear on, which absorbs a rough cut of a few millimetres. What it cannot do is span a hole cut oversize by half an inch or more, because the flange then has nothing solid under it and the vent rocks underfoot. Measure the opening before ordering.
How do I measure for a replacement vent?
Measure the duct opening, not the old cover. Pull the existing vent out, measure the hole itself across the width and the length in millimetres, and match that to the duct dimension listed on this page. Vent sizes are named for the duct, so a vent called 4x10 has a face larger than 4 by 10 inches. Measuring the faceplate is the single most common reason a size arrives wrong.
What happens if I order the wrong size?
Email support@khansupply.co with your order number and the millimetre measurements of your opening, and we will work out which size actually fits and sort out the exchange. Every Khan Supply vent also carries a 2-year warranty against defects, which is separate from a fit exchange.
What does shipping cost?
Nothing. Shipping is free on every order across North America, on a single vent and on a 5-pack alike. You will get tracking by email once the order is on its way. If a vent arrives damaged, photograph the box and the part and email support@khansupply.co, Monday to Friday 9 to 5 ET, and we reply within one business day.
Every Khan Supply vent is all metal, not plastic, and ships free across North America with a 2-year warranty. If a size is wrong, email support@khansupply.co and we sort out the exchange. Mon-Fri 9-5 ET, one business day reply.
Not sure of your size? · All sizes and free-area figures · Every size we make