I want to fit three wooden Venitian blinds into a square bay window. Do I still send you exact measurements allowing you make the adjustments for them to fit accurately. Many thanks, Eileen Gibson

Many thanks for the clarification, please see below:
Measuring for a box bay:
This is if you would like your front blind to span the entire width of your bay window and the two side return blinds will overlap the large blind at the front:
  1. Measure the full width of the long window at the front of your bay window. Use this as the width measurement for your front window blind.
  2. Obstruction checks – Measure the distance from the frame of your window to the outside of any obstructions, such as handles or vents. Make a note of this measurement.
  3. Calculate the depth – For your front window blind, add the depth of any window obstructions such as handles to the depth of the headrail. For wooden blinds this is 7.5cm.
  4. Mark the total depth of your front window blind on each side of your square bay window.
  5. Measure side windows – Measure from the total depth mark (which includes the depth of the blind headrail) to where you would like your return blind to finish. This is the width measurement of your return blind. Repeat this step for both return blinds.
  6. Measure the height of your square bay window in three places. Use the smallest measurement as your drop for all blinds.
  7. Now enter your width and drop measurement, then select Recess as your sizing option. Repeat the process for your side window 1 and 2. 
  8. Deductions – if selecting ‘recess’ as the sizing option, we will make a small deduction to the width of the blinds, which accommodates the brackets.