Box Bay Window Measuring Guide

Standard Window Measuring

Measuring for Angled Bay Windows

Measuring for Conservatory Blinds

See BRACKET IMAGES and SIZES at foot of page.

Please note, these instructions are for top fixing in all cases.
You’ll find:

  •  Things to consider

  •  Measuring for bay windows

  •  Measuring instructions. 


Things to consider

Are there any obstructions that will hinder the operation or fitting of the headrails?

Is the fixing area clear with no ridges of PVC?  i.e. Is it a flat fixing surface?

If not, do you need to make allowances or consider how to get your fixings?

Do you need to make allowances for dado rails, phone sockets ect.? Or anything that will hinder or stop the blind from working properly?

Box bay windows within a recess

Measure the width of the front window first: top, middle and, bottom. Make a note

of the smallest measurement, then deduct 1cm to give you clearance. 

This will be the size when you order your blinds. (Choose (Exact) Blind Size option).

  • Now the drop. Measure all around the bay, and find the smallest drop measurement from your fixing point. Make a note of this.
  • For the sides: if you have handles, then the front blind and the side blinds should sit just in front of the window handles. See Fig (1) for a birds eye view.
  • Different blinds have different headrail sizes. Below is all the information you will need to calculate the clearance required.
  • For example Fitting wooden venetian blinds with 35mm slats, 46mm headrail and 40mm handles. 

      We need to measure 86mm from the window frame in both corners. Then put a mark on the ceiling:

      this is the position the front face of the blinds’ headrail will sit. From that mark, we measure to the side recess, 

      the left side and the right side. Again, make a note. This gives us the width of the side blinds. 

      Then deduct 1cm from both measurements to allow for clearance. This will be the size you use when ordering your blinds. 

      When you enter your measurements on the website, you need to select (Exact) Blind Size. 

      This option means you require your blinds made to the exact sizes, 

      and you have made allowances for the 1cm clearance on all three blinds.

Box bay fig 1 and 2

For Open Bay windows

  • Measure the width of the front window first: the top, middle, and bottom make a note of the smallest measurement, then deduct 1cm

       to give you clearance this will be the size when you order your blinds.(select the (Exact) Blind Size option).

  • For the drop, measure all around the bay. Find the smallest drop measurement from your fixing point, and make a note.
  • For the sides: if you have handles, then the front blind and the side blinds should sit just in front of the window handles see Fig (2)  for a birds eye view.
  • Different blinds have different headrail sizes. Below is all the information you will need to calculate the clearance required, including your handles.
  • For example Fitting wooden venetians with 35mm slats, 46mm headrail and 40mm handles. We need to measure 86mm from the window frame in both the corners. Then put a mark on the ceiling. This is the position the front face of the blinds headrail will sit.
  • As in Fig (2), you need to decide where you want the side blinds to end: either at the edge of the window frame, or possibly 20cm or so wider, to provide more coverage. When the blind is closed, you may still be able to see some of the window at certain angles. This is due to the blinds standing off the window, to allow for handles and the headrail. Consider your fixing points. Is it still possible to fix the blinds if you make them wider?
  • From that mark, measure to the side recess, left side and right side. Then make a note. Now you have the width of the side blinds.
  • When you enter your measurements on the website, you need to select (Exact) Blind Size. This option means you require your blinds made to the exact sizes, and you have made allowances for the 1cm clearance on all three blinds.
  • Please note, this information is for your guidance only. It is how our trained fitters measure for bay windows. We can not be held responsible and do not accept responsibility for errors and possible oversight on your part when you measure and supply us with your dimensions.
  • The sizes you provide are your responsibility. Refunds or replacement blinds free of charge will not be possible if you measure incorrectly.
  • Depending on the size of your window frame, you may find there is a small amount of glass showing in the corners of the bay. This may occur when the blind is closed, and happens due to the allowance for handles and the headrail. When measuring, look down the window from your marks on the ceiling. This will show you what position the blinds need to be in for total glass coverage. In some cases, it may have to be a compromise.
  • If you are unsure, we suggest that you order and fit the main blind first. Then order the side blinds to fill in the gaps. However, if you choose this option we cannot guarantee the blinds will be a perfect match in colour, or that the slats will line up.

Vertical Blind Box Bay Example.

Image title Vertical Blind headrail box bay example.

Pictures 1 and 2 show a vertical blind within a corner. This is how you would set the headrails. The pictures show a face fix bracket option measurement (A) is 96mm. This type of bracket will provide 4cm handle clearance at the back. You would deduct 9.6mm from the full width of headrail (B) so it butts up to headrail (A). Deduct an additional 1cm from all your headrail widths for fitting clearance.

For any additional butting up tracks in corners, deduct 96mm. Order the blinds as (Exact). Use the same principal for all blind types.

If you are top fixing vertical blinds, allow 4cm for the louvres overhang at the back of the track, plus your handle depth. If  your handles are 4cm, then deduct 8cm from any butting up tracks in the corners. Remember to deduct the 1cm additionally from all your headrail widths for fitting clearance. See all the bracket pictures with dimensions and our top fix bracket chart below, Use the same principal for all blind types.

It is important for us to have accurate measurements for your blinds, as they are made to your specific measurements. If you have any problems or questions, please contact us. 

Wooden Blind Box Bay Example.

Image title

Picture 3 shows how you can substitute the brackets when measuring with a piece of card. This example is for 50mm wooden blinds that will be top-fixed or side-fixed within a box bay or conservatory. Our handles are 40mm and the bracket width is 66mm. Cut card that is 10.6 cm long.


So from the window frame we need to mark away 10.6 cm. This is where the front of the blind headrail will sit. Position (1) is where the side blind will start from. Decide where you wish the width of the side blind to finish, if the bay window is a recessed type (See fig 1). Remember to deduct an additional 1cm from the widths to allow for fitting clearance order your blinds as exact.
If you have open bay type (see fig 2) then you only need to deduct 1cm from the main blind at the front of the bay for fitting clearance. Order your blinds as exact. Use the same principal for all blind types.


NOTE: Child safety loose cords and looped cords.
Installation height not known.
“Please advise us immediately after placing your order quoting your order number via email, if your blind headrail is to be installed in excess of 2.5 metres from the floor. This is essential so that control lengths can be adjusted, otherwise blinds will be supplied with controls compliant with EN 13120 so will be supplied up to a maximum of 1 metre long.”
*If drop is greater than 2.5m then cord and chain length must be less than or equal to drop of blind minus 1.5m.



Box bay bracket sizes

Headrail width dimensions for top fixing in bay windows all blind types.

Remember: you need to add the handle depth to these dimensions.


The dimensions given are for our M2M blinds and do not represent an industry standard.

Wooden venetian blinds.

 Image title Wooden Venetian Blind box bracket top fix.

 25mm slats bracket width top fix 46mm + your handle depth
 35mm slats bracket width top fix 46mm + your handle depth





Image title Wooden Venetian blinds top fix bracket.


50mm slats bracket width top fix 66mm  + your handle depth






63mm Wooden Venetian Blind Box bracket to fix.



              63mm slats bracket width top fix 76mm + your handle depth.





Standard aluminium venetian / wood effect venetian blinds.

Image title standard venetian blind swivel bracket top fix



25mm slats bracket width top fix 31mm includes bracket + your handle depth.
16mm slats bracket width top fix 31mm includes bracket + your handle depth.




Pleated blinds.

Image title Pleated blinds top fix clip.




Pleated blind headrail top fix 22mm + your handle depth.





Roman blinds.

Image title Roman blind sidewinder swivel bracket.



Sidewinder with headrail top fix 44mm + your handle depth.

*Note headrail will provide 35mm clearance from handles.



Image title Roman blind Cord and Cleat top fix bracket.



Cord & Cleat top fix 45mm includes bracket + your handle depth.

*Note headrail will provide 35mm clearance from handles.




Roller blinds.

Pic: 1

Image title Roller Blind top fix bracket.


*Note roller blinds over 2m are upgraded to larger barrel size.

we can match all blinds so all manufactured on the larger barrel size.

You would need to allow for this in the corners by measuring with the larger bracket. See pic 2 and 3.

Ø32mm barrel width up to 2m top fix 49mm + your handel depth.

Or reverse roll will place the fabric 40mm from window frame so should miss handles.

see Pictures 2 and 3.
Ø40mm barrel width from 2m to 3.0m top fix 73mm + your handle depth.




Pic:2*

Ø40mm barrel width from 2mt all fabrics marked with an *


*Note roller blinds over 2mt are upgraded to larger barrel size.

We can match all blinds so all manufactured on the larger barrel size.

All Solas fabrics marked with an * will have this bracket.

You would need to allow for this in the corners by measuring with the larger bracket. See picture 2.

Ø40mm barrel width from 2m to 3.0m top fix 73mm + your handle depth.

Or reverse roll will place the fabric 55mm from window frame so should miss handles.






Pic (3)
Image title Ø45mm barrel 2mt plus fabrics NOT marked with an *


*Note roller blinds over 2m are upgraded to larger barrel size

we can match all blinds so all manufactured on the larger barrel size.

All fabrics NOT marked with an * will have this bracket.

You would need to allow for this in the corners by measuring with the larger bracket see picture 3.

Ø45mm barrel width from 2m to 3.0m top fix 81mm + your handle depth.

Or reverse roll will place the fabric 65mm from window frame so should miss handles.




Vertical blinds.

Image title Vertical blind top fix clip.

89mm Louvres allow top fix 40mm this allows for free rotation of louvres from handles + your handle depth.


127mm Louvres allow top fix 63mm this allows for free rotation of louvres from handles + your handle depth.