How to Measure and Replace a Wall Mount Heat Register or Grille

After repainting and remodeling a room, the finishing touch should be replacing your old, dated heat registers or grilles with sleek new versions. Heat registers are the grille work that covers the opening of a heating systems duct work into your room. While many homes typically have white clad aluminum grilles, today’s contemporary heat registers are made in a wide variety of styles and materials, and can add elegance to any room.

Replacing your old heat registers with a newer model is an easy DIY job, requiring nothing more than a screwdriver and a yard stick or tape measure.

Measuring the space

In newer homes, the ventilation openings tend to be a standard size. With older homes, the opening may be odd sized and irregular. To determine the size of vent cover you need, the first step is to remove the existing cover. This is done by unscrewing the two nails that hold the vent cover flush with the wall, then pulling the vent forward and out of the opening.

After the cover has been removed, use your ruler to measure the vent opening in the wall. Measure the width first, and then the length, since this is how the grille dimensions are cataloged. This W x L dimension represents the wall register size you need.

In the cases of an irregular sized opening, there are a couple of alternatives. For dimensions that are just shy of an inch from the standard size, round down to the next nearest size of vent cover. For example, in my home where the vent openings are 7 x 12.5, I round down to use 6 x12 heat registers. They sit a little loose in the opening, but not so much that anyone will really notice. If the dimension is more than an inch, you may have to order a custom grille cover.

Here are a few resources you can explore for custom grill covers:

Installing the new heat register or grille cover

Once your replacement grilles have arrived, they are very easy to install. Simply remove them from the box, unwrap, and then gently press into the wall opening. Line up the screw holes and use a screwdriver to attach them to the metal screw brackets. That’s all there’s to it.

Before tossing those old grille covers in the garbage, consider recycling them instead either by advertising them on or bringing them to your local recycling center.

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