Measure the width of your fireplace by measuring across the fireplace opening from edge to edge. The average fireplace width is 36 to 42 inches.
Measure the height of your fireplace by measuring from the hearth to the top of the opening. The average fireplace height ranges from 28 to 32 inches.
Measure the depth of your fireplace by measuring from the front of the hearth to the back of the firebox. Most fireplace screens need a minimum of 6 inches from the firebox.
Measure the fireplace screen. For screens that bow, measure from left to right edge rather than the entire width.
Know the different styles of screens, there are only three categories. The Flat Panel fireplace screen is designed to lean against the fireplace opening and must be a half inch wider and taller than the opening. Curved or Bow Front screens are curved with the edges designed to rest inside the fireplace opening, "wrapping" around the fire. Leave a quarter or half inch gap between the sides of the screen and the fireplace wall. Curved screens have an open top that should be as tall as your fireplace opening. Three and four panel screens have adjustable folding panels; the screen should be a half inch taller and wider than your fireplace screen. All of these screens should either rest on the floor or have a gap less than an inch between the bottom of the screen and the floor.