How to Accurately Measure Your Windows for Blinds

If you want your window furnishings to fit well, then knowing how to accurately measure your windows for blinds is important.

You might also be thinking that this type of thing isn’t up your alley, but the good news is that it’s super easy. In fact, it’s DIY that a 10-year old could follow. Once you know exactly what you need to do, it’ll be a breeze. And that’s exactly what we’ll be aiming for here. With three simple tips, you’ll be able to get that perfect fit no matter the type or size of blind. Trust us, they’ll be the best DIY blinds around.

1. Determine How You Want to Mount Your Blinds

‘Mounting’ a blind is simply about figuring out where it’s going to sit. That is to say, inside or outside the window frame. There’s no right or wrong answer, it’s all about personal preference as they give off different looks.

Inside mounting tends to be the winner in most cases as it simply has a neater, cleaner look about it. On the other hand, an outside mount will help block more light as it goes over the window frame. Some window frames are too shallow for the mounting brackets, so an outside mount suits this situation as well.

2. How to Measure Windows for Inside Mount Blinds

Before diving into how to install window blinds, make sure you have a metal measuring tape handy. You want your measurements to be accurate, and this is how you can ensure you do that. 

Another thing to remember is that you should always measure in millimetres. And if you already know you want an inside mount, see the below. Otherwise, move onto the next point.

  1. Check there’s enough room: Inside mounted blinds make for a snug fit within the window frame. But that also means that you need to make sure there’s plenty of room to accommodate this. Ensure there are no obstructions like handles for instance that could get in the way. You want enough ‘architrave depth’ as we call it, so the blinds have room to sit.

  2. Privacy/ Light gaps: Your blinds should be able to operate without catching, and for this reason there’ll be a small gap at each side. Depending on the type of window this mightn’t be an issue, but if privacy is a concern then it’s worth thinking about an outside mount. It may also pose a problem if you want complete blockout as light gaps can occur.

  3. Start measuring:

Measure the depth of the window frame to ensure you have enough space for the blind to operate.


    a) Measure the width inside the window frame in 3 places from left to right. That is the top, middle and bottom.

    b) Make a note of the smallest measurement.

    a) Measure the height inside the window frame in 3 places from top to bottom.

    b) Make a note of the smallest measurement.

NOTE: We’ll make slight deductions to ensure the blind fits your window.

3. How to Measure Windows for Outside Mount Blinds

For inside mounted blinds we looked at measuring the inside of the architraves. Here, we’re going to do the exact opposite, measuring the outside from one architrave to the other. However, not all windows have architraves. In such cases, it’s best to go with the wall above or sides of the window.

  1. Take some time to decide how far beyond the window you want your blinds to sit. Since a headrail will be fixed above, this will be a good point of measurement. Again, ensure you’re aware of any obstructions. 

  2. Start measuring:

a) Measure the exact width you would like the blind to cover.

b) Measure to the outside of the architrave or at least 50mm past the window opening.


a) Measure the exact height you would like the blind to cover. Measure this from the left, middle and right as you do so. 

b) Measure outside of the architrave or at least 50mm past the window opening.

NOTE: The blind will be supplied at the sizes provided (we won’t make any deductions).



And there you have it! A simple, straightforward guide to measuring accurately for your blinds. This one won’t have you ripping your hair off, and will ensure your blinds fit just the way you wanted them to. Of course if you have any questions or trouble at any point with this, we’re always here to help. Just reach out to us via the Livechat, e-mail, or give us a call. You can also check out our other blogs which include everything you need to know about buying new window blinds.


How to Accurately Measure Your Windows for Blinds
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