How To Measure For 2 On 1 Headrail Window Blinds

In this quick tutorial, let’s take a look at how to measure correctly for 2-on-one headrail window blinds using an inside mount example. Measuring for 3-on-one headrail blinds is similar.
White Faux Wood Blinds is the case in the picture. For the size of the window, it was necessary to split the faux wood slats into two sets. However, it was needless to split the single headrail into two.
So, this is what it looked like once the faux wood blinds arrived and were put up.
Faux Wood Blinds - 2-On-One Headrail Measuring Details
Faux Wood Blinds – 2-On-One Headrail Close Up
Notice the single headrail and two stacks of slats pulled to the top. The two controls (lift cords and tilt wands) for each side of the faux wood blinds are on the left and right end of the headrail.
Provided the minimum sill installation depth is fine, measure for the 2-on-one headrail window blinds WIDTH first. The red arrows show you how.
Take 3 separate WIDTH measurements while measuring from left to right. 
First, take the measurement to the middle of window divider (mullion). 
Next, measure the distance to the window frame from there. 
Round the numbers off to the nearest 1/8” and record your first set of the WIDTH measurements.
Now, you have two numbers for your first WIDTH measurement set. Repeat the same two more times and write down the results.
Once you have three sets of numbers, keep the smallest one (the narrowest width).

Next, measure the TOTAL window WIDTH 3 times. 
Record the smallest number (the narrowest width) rounded off to the nearest 1/8”.

The final 2 WIDTH numbers on the order sheet will be the narrowest measurements.
First, put in your TOTAL WIDTH measurement (the smallest number).
Second, put in the narrowest set of the two measurements from left –to the window divider (mullion) – to the right window frame.
The TOTAL WIDTH number must equal to the sum of the narrowest two measurements from left to right.
Example: Total Width = 66", First part of the window width = 40", Second part of the window width = 26"; 40" + 26" = 66"
Record the exact numbers. The factory will take deductions.
Of course, you’ll need to measure the HEIGHT as well. To do that, take three separate measurements from top to bottom of the window.
The largest number (the longest height) rounded to the nearest 1/8” is the exact HEIGHT.
So, now you know how to do it. The steps are the same for 3-on-one headrail window blinds, except you’ll need to measure THREE separate distances across the window width.


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