How to Measure Floor Vents

Floor vents cover the air duct openings in your home and allow you to control airflow in the room through a lever on a damper box.
These floor vents, also known as air return grilles, heat vents, and floor registers, consist of two parts: the damper and the grille. They come in a variety of materials such as brass, wood, metal and plastic and can add a lovely accent to your home décor when chosen with care. Order new or replacement vents by measuring the opening and finding vendors who offer vents in your size.

Step 1

Remove the floor vent from the ventilation opening. Some vents can be pulled straight out of the hole, or you may need to use a screwdriver to release the screws that secure the vent in place.

Step 2

Remove a vent that is screwed into the floor with a small, flat-headed screwdriver. Turn each screw to the left with the screwdriver to loosen the screws until you can remove them by hand. Remove the floor vent by lifting it in a straight vertical motion from the opening.

Step 3

Measure the vent opening with a tape measure or ruler. First, measure the width, then the length. Write down the measurements of width x length on a piece of paper. This is the way floor vent manufacturers list the sizes for their vents — not length x width.

Step 4

Turn the vent you previously removed over, so the bottom side is facing up. Measure the inside of the vent grille to ensure it matches your floor opening measurements. If there is a discrepancy, check that the vent is properly sized to the hole, or if it is loose. You want a replacement vent sized to the opening, rather than an improperly-sized vent. Go with the floor measurement when approaching a vendor if the two measurements do not match up.

Step 5

Measure the floor opening a second time if there was a discrepancy between the opening measurement and the bottom of the inside vent grille. If the two measurements matched up, bypass this step.

Things You Will Need

  • Screwdriver
  • Tape measure or ruler
  • Paper
  • Pen or pencil


  • Many ventilation openings are standard sizes, but other may require a custom-sized floor vent. These are usually more expensive. Some vendors recommend going with a slightly smaller vent if the differentiation is less than 1 inch. If you do not close off your vents often and do not have a need for a secure, tight seal, this may be a more affordable option.

About the Author

Abaigeal Quinn works as an international entertainment broker in the United States. She is a former news editor and insurance agent who began writing for a daily newspaper in 1995.