The information contained in this article is valid for 1 or 2 inch wood, faux or metal blinds.
Measuring for your blinds is the most important step in the entire process. You need accurate measurements to order the blinds and receive the correct product. The first thing you must do when measuring for blinds is to determine if you need inside mount or outside mount. Inside mount will fit the blinds within the window frame, while outside mount will fit the overlap of the window opening and usually completely cover the width of the frame.
You may not have a choice! If you do not have at least 1 inch of flat surface to the sides and top you may be forced to use outside mount blinds. An experienced installer can get by with 1 inch of flat surface at the top or the side but it is a much more difficult installation.
Yes that is correct! You can install a 2 inch blind with only 1 inch of surface. The blind just projects into the room a bit.
Inside mount To find the correct width to order, measure the exact distance between the inside surfaces of the window frame at the top, middle, and also the bottom then use the narrowest measurement as your width. When reading your tape measure you should round down to the nearest 1/8". Always round down for inside measures.
To find the length (or height), measure the exact distance from the inside surface at the top of the window to the bottom sill at the left, middle, and the right then use the longest length. In most cases blinds look and work the best when they rest on the window sill. No one is ever going to notice extra 1/2" of length and this keeps them from blowing in a slight breeze. If you prefer for the blinds not to touch the windowsill, you should deduct 1/4". If there isn't a sill, then you should measure the length to the point where the blinds are to reach.
Outside mount To find the width, measure the exact distance between the outermost points where the blinds are to be placed. This is usually from the outer edge of the window casing to the opposite side. Again be sure to measure to the nearest 1/8" but this time you round up. There are times and places where it is not desirable to cover the entire window casing for some reason. If that is the case please keep in mind that for the best of light control, the width measurement should extend at least 3/4" beyond the window opening on each side.
To find the length, measure the exact distance from where the top of the blinds are to be placed to the top of the windowsill. Once again please keep in mind that in most cases blinds look and work the best when they rest on the window sill. If there isn't a sill, then you should measure the length to the point where the blinds are to reach.
A word about ordering Be sure to inform the order person when you order your blinds whether they will be mounted inside the casing or outside on the casing or wall. Most fabricators will deduct 3/8-1/2" from your IB measurement to allow for proper installation and functioning of the blind. OB blinds are made to the exact size your order. Trust me it is really tough to install a blind ordered for outside mounting on the inside of the casing.
