Measuring for Blinds
Depending on where you would like your blinds to sit will determine where you measure from.
Take this measurement if you plan on hanging your blinds or shades inside the window frame. This creates a very clean and minimal appearance which emphasizes the casing or trim around the window. This can be done with and blind, honeycomb, roller or roman shade.
Width: Measure the width exact from inside of frame to inside of frame at the top and bottom of the window. Always use the smallest measurement. Most styles will require room for hardware so subtract 1/2 inch total which will allow for 1/4 inch on both sides. This is the tight measurement. Most blind companies will be able to figure out the tight measurement so always give them the exact size.
Height: measure the height exact If you plan on ordering a custom blind as you can get it to unravel the full length without any extra slats sitting on the sill. If you plan to buy a stock blind from the store chances are it will be too long as most styles come in 3-5 different lengths.
This measurement is used if you would like to mount the blinds to the outside of the frame which typically sit on the casing or trim. Can give the appearance of a larger window or hide unsightly and boring casing or trim. Most blinds or shades can be mounted on the outside of the frame. I would stay away from doing this with roller shades as this may look out of place and unfinished.
Width and Height: Measure outside edge of casing to outside edge of both width and height. You could also have them set in from the edge, just measure exactly where you would like them to sit.
A couple things to keep in mind
Consider window opening and locking hardware as they may be in the way of your new blinds and you may need to set them farther out into the room to be able to pass these pieces. Also, check the jamb or frame depth. When tilted the blinds may hit the glass if the slat width is wider then the jamb depth, which can create the appearance of an overly bulky, improperly measured blind.
Word of the day: Jamb Extension
A flat piece of wood that extends past a window or door frame to finish the interior. Example: If the wall depth is 6-1/2 inch and the window frame is 3-1/2 inch then the jamb extension would be 3 inches deep.