Vertical Blinds Measurement Guide

Vertical Blinds can normally be fitted either onto the face of your window frame using brackets, either onto a batten or directly onto the wall  above - we call this Overlap Fitting - or by attaching using clips to the lintel within the recess - we call this Recess Fitting.  

We do not need to know whether the measurements are for Overlap  or Recess in order to make the appropriate manufacturing adjustments to ensure a perfect fit - you just need to advise us which type of fixations are needed. 

When measuring, for whichever method, we always recommend the use of a steel tape measure and to take the measurements in millimeters (to the nearest 0.5cm) at three stations in either direction for both width and drop. 

If you wish to install the blind so that it Overlaps the window, measure the exact area you wish the blind to cover, width and drop.   You should also ensure a flat surface of at least 75mm is available for mounting the blind is available above the window.   If possible always allow a minimum of 100mm overlap on both side as this will minimise the amount of light "leakage" passing around the edges of the blind. The length of the drop is up to your personal preference but again a minimum of 50mm overlap is recommended unless the material is to fall close to the floor, or window shelf, when usually a gap of 20mm to 25mm is recommended. 

If you wish to "Overlap" you will have to choose between the standard brackets ( which alllow extension of the rail between 60-108mm and which will be supplied at no additional cost) or the larger bracket which allows extension of the rail of up to 175mm at an additional cost.  You will not have to specify how many of the brackets you require as these will be determined by the manufacturer dependent upon the length of rail ordered.

If you wish to install the blind within the Recess, measure exactly in each direction at the three stations and use the smallest measurement for both width and drop.   We recommend that both the rail length measuremenst is reduced by between 0.5cm to 1.0cm to allow for ease of fitting the rail within the recess and the overall height od the drop reduced by approximately 2.0cm to allow free movement of the vanes above the window shelf. When fitting within a recess, choose clips as the fixation method which will be supplied by the manufacturer and which will have to be affixed at regular points on the upper rebate.

 Blackout Blinds UK

The minimum width is 30cm and the maximum width is 597cm

The minimum drop is 30cm and the maximum drop is 597cm


In addition to the above details you will also need to decide which type of control you would like for your blind, either a  Chain and Ball  mechanism with a cord, which controls the angle that the vanes are set and a continuous line which controls the opening or closing of the stack, Rod Control mechanism which allows manual transfer of the stack to the left or right and, by twisting the rod, the angle that the vanes are set or choose the motorised opotion.

It should be stated that Rod controls are not as robust as the Chain and Cord mechanisms and are best used in situations where there is a slight worry about safety -such as "anti-ligature".  The Rods are supplied in three parts and have to be glued together using superglue (not supplied) before clipping to the rail.  The rods can be sawn to shorter lengths if required.

If you wish your rod or chains and cords to fall below the level of the vanes, such as when a window is at a high level, you will find a box in the ordering section that allows you to specify its length. Otherwize leave the box blank and the blind will be supplied with controls to the standard lengths.

If you decide on a Chain and Cord mechanism you will also have to decide whether it should be on the Left  or  Right hand side and there are in fact eight different stacking options - please see the diagram below.




Please do bear in mind for all measurements any obstacles, such as opening windows (this is particularly pertinent in deciding the most suitable stacking arrangement) handles, radiators, shelves etc. that could interfere with the perfect operation of your blind.

Also consider the possible interference of the operation of the blind by windows that open inwards.

It is not advisable to measure for a Recess fitting in this case.

If the opening window turns in a vertical plane, then arrange for the stack to be away from the hinged side.

If the window rotates in a horizontal plane, then, if possible, arrange for the stack to be parted to either sideand allow a good verlap for the vanes to clear the window and allow it to open normally.

To calculate the minimum overlap needed divide the window recess opening width by 127mm or 89mm (to calculate the minimum number of vanes needed) - each vane requires 1cm and the mechanism also requires 1cm. Add this additional sum to the window width and this will give the minimum rail length required but also bear in mind the recommended overlaps for light control.