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How to measure for a blind

You will need a steel tape measure, which is generally more accurate than a wooden ruler or cloth tape measure, a notepad and pen and you may need a step ladder but for Bay windows you will also need a Pencil and a Ruler. The first thing you need to do is decide whether you want your blinds inside the window recess or whether you want your blind on the outside of the recess to cover the window entirely.

Now check if there are any obstructions inside or outside the window recess where the blind will hang, for example look out for handles, part tilling, or windows that open inwards and avoid them, If you need advice, call us or even send us a digital photo.

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What does it mean = Terms of use

What is the child safe legal measurement?

The Child safe law was introduced to stop the Death of children from Blind cords, therefore you have to take the Child safe measurement by Law.

Go to for more information.

How to do this

Measure from where you want the TOP of your blind to be installed, down to the floor. ignore anything that may be in the way, for example radiators or furniture.

If measuring for kitchen or bathroom blind, then ignore the Bath or kitchen worktop, the measurement has to be from the Top of the blind to the floor.

Inside recess size

if you want to fit your blind within the window area, then you need to order as INSIDE RECESS SIZES You should take the measurements Three ( 3 ) times, as shown in the diagram.

Step 1

Start with the Width Measurement

Measure 3 times, at the Top, Middle and Bottom for the Width.

Step 2

Then Take the Drop Measurement

Measure 3 times on the left, Middle and Right for the Drop.

Step 3

Then Take the Child Safe Measurement

Measure from the Top of the window to the Floor.

Step 4

Enter in the smallest measurements you took for the Width and Drop

We will then deduct 1cm from the overall sizes to create the Inside Recess Sizes.

Outside Recess Sizes

If you want your blind to fit outside the window, to cover the entire window area, then this is called Outside the recess

Measure as Above but add on 10cm to the width and Drop Measurements

If you have a wooden baton above the recess, we advise you to measure this as your Blind width and from the top of the baton to where you want the blind to finish as your Blind drop and don’t Forget to take the Child Safe Measurement as advised above.

Blind sizes

If you want your blind to be an exact size, then order your new blind as Blind Size.

If you choose Blind Size, we will use your measurements as the Total size of the blind which includes the brackets and mechanism, but the fabric part of the blind will be smaller than the sizes you provide. The amount the fabric differs, varies depending on the type of blind ordered.

Blind Size is Important when measuring for Bay Windows or if you want the Blind to fit inside an obstruction.

Bay windows

If you have a bay window, then you must order your new blinds as BLIND SIZE.

Whether you’ve got a square ‘box’ style or angled bay window, we’re here to help you get the right measurements to ensure your new blinds fit perfectly.

With bay window blinds, the measurements you need to take differ for the type of blind you’re looking to install, we list the different headrail Depth measurement allowances by blind type below.

Our handy guide makes measuring for your square box or angled  bay window blinds simple, but as always, get in touch should you have any queries.

Establish which type of bay window you have from the example picture. There are many types of Bay Windows, so don’t worry if you don’t see your exact window in the picture as the measuring principle is the same.null

Measure how far the Window Handle projects OUT from the Window FRAME and then transfer this measurement onto your note pad.


Now decide on how you want the layout of the blinds to be. Do you want them to Butt up to each other or Cross over each other.
Now decide on your Blind type and look at the Size chart to see how far that particular blind projects forward.

Roller blinds

Please note: due to the cloth cover always being narrower then the bracket to bracket exact size,  unless you have a large corner window frame work, there will always be areas of glass that aren’t covered fully by the blinds, this is especially noticeable if you’re looking to install blackout blinds and applies to ALL roller blinds.
You also need to decide whether you will be  top or a face fixing as this will affect your allowances when measuring. Top-fix bracket allowance is 50mm(for blinds up to 2000mm wide), and 70mm(for blinds over 2000mm).
Blind Width Face Fixing Bracket Depth
Roller Blind under 200cm wide 60mm
Roller Blind over 200cm wide 80mm
Roller binds
Wooden blinds

Wooden blinds

Firstly, you need to establish the headrail depth for the slat size of wooden blind that you’re measuring for using  the chart below.
Slat SizeRail depth
50mm slat wooden blind70mm
35mm slat wooden blind42mm

Vertical blinds

With vertical blinds, be careful when adjusting your measurements – you need to be aware of your bracket sizes when ordering this kind of blind for a box or square bay window and pay particular attention to the size of the slat.
Slat Size Rail depth
90mm Vertical Blind Slats 70mm
Vertical blinds 1
Pleated blinds

Metal Venetian blinds 

Firstly, you need to establish the headrail depth for the slat size of Metal Venetian blind that you’re measuring for using  the chart below.
Slat SizeRail depth
50mm slat wooden blind70mm
35mm slat wooden blind42mm
Roman Blinds

Roman blinds

The headrail depth  for our Roman blinds is 45mm.
Pleated blinds

Pleated blinds

The headrail depth for our pleated blinds is 35mm. If you need any further help with other blind types give us a call or send an email. Go to the contact us section.

Step 5

Creating the angles Using A4 card or A4 paper

Using A4 card or A4 paper, you need to create two templates to represent the bracket projection of your blinds and the previous measurement you took for the Window handle projection. Add the two sizes together and Measure and Mark a line on the Paper of the Sizes you need as previously mentioned and then Cut out, along the lines, two ( 2 ) Identical pieces. These now represent your bracket and window handle projections. Now Place them onto the window sill so that they touch the window frame. One on the left side and one on the right of the angle and slide them towards each other until the points or corners of the papers meet. They should not overlap


Step 6

Now that you have all of the Corners of the bay window covered with your Paper / Card Templates , Measure the front edge of them or the Point upon which both templates touch each other, to now establish your new Width of your blind. Measure from the Left window first placing the tape measure on to the first POINT of your template and measure towards the 2nd Corner and the 2nd Point of your template. This is your first window Width measurement for you new blinds.

Now repeat this process for each corner within the bay window.

Step 7

Measuring the drop

For all options, you simply measure from the top of where the blind will be fitted normally the underside of the ceiling, to the window sill or wherever you wish the blinds to hang to. Then just deduct a little from your given size for clearance allowance. normally 1cm


By now, you'll have all the measurements you need to order blinds for your angle bay window - just remember to order blinds as BLIND sizes. 

Professional measuring service

If you are unable or unsure on how to measure, then don’t worry, you can take up our Professional Measuring Service. 

Contact us for the cost of this service, as it depends upon how far away you are from our head office.