Measuring for Inside Mount
STEP 1: Measure the inside width of your window opening in 3 locations - the top, middle and bottom. If they vary, record the smallest of your 3 measurements to the nearest 1/8". This is the width you will order, we will make the necessary deductions for inside mounting. The standard inside mount deduction on all wood and faux wood blinds is approximately 1/2" from the width you specify. This allows space for the blinds to operate and room for the mounting brackets. The standard width deduction on the valance (decorative molding that covers the headrail) is 1/8".
STEP 2: Measure the height at 3 locations - the left side, middle and right side. Record the largest of the 3 measurements. This is your ordering height.
Measuring for Outside Mount
STEP 1: Measure the width of the area you wish to cover. If space allows we recommend adding 2-3" (1-1 1/2" each side) to this measurement to help eliminate light seepage. This is your ordering width and will be the overall measurement of the blind (valance will be approx. 3/4" wider than blind).
STEP 2: Measure the height of the area you wish to cover. This is your ordering height. You need 11/2" to 2 1/2" of flat space for your mounting brackets (varies by blind, the specifications page gives the exact flat space needed for mounting each type of blind). The factory will make your shade (including the headrail) to the width and height ordered. Generally 3" - 4" added to the height of your opening (including molding or framework you wish to cover) will allow you room to mount above the window frame.