Important Tips for Measuring Windows for Blinds

measuring windows for blinds

Are you looking to install new blinds in your home?

First of all, great decision! New blinds can really upgrade your home. However, in order for your blinds to look their best, you need to make sure they fit your window properly. 

And for that, you need to do some measuring. 

What does that entail?

Read on to learn the most important tips for measuring windows for blinds. 

Inside vs Outside 

The first important decision you need to make when measuring your windows for blinds is whether you want to mount the blind on the outside or inside of your window frame. 

Mounting on the inside provides a clean look to your window frame, and it allows visibility for your window molding. However, you will need to make sure your window has enough depth if you want your blind to fit evenly with the window molding. 

Outside frames are great for those who would like their windows to appear a bit wider and longer. Plus, if you feel like your window is unattractive, an outside frame can help hide this. You will also get more privacy and greater light control with an outside frame. 

In addition to inside our outside, you will also need to choose between horizontal and vertical blinds if you haven’t already. These blinds need to be measured differently, so you will have to decide this beforehand. 

Time to Measure

Once you’ve decided on the style, it’s time to measure. Grab a measuring tape, pen or pencil, and a piece of paper, or something else with a straight edge. 


  • Measure the exact width of the window at the bottom, middle, and top
  • Use the narrowest width to give to the manufacturer, without making any deductions
  • Now measure the right, left, and middle, and choose the longest height to give to the manufacturer

Horizontal- Outside 

  • Find the exact spot where you plan on placing the blind and measure the width
  • Then, add some space / centimeters (around 1cm to 3cms on each side) for overlap
  • Measure the height from where you want to headrail to be to the base of the sill or to where the blind is supposed to end 
  • Add about a 1.5cms to the height to more easily control the light


  • Measure the window from sill to sill in three evenly spaced out places. Give the smallest dimension to the manufacturer
  • Do the same with the height, measuring the sill top to bottom in three different places, and record the longest height
  • Measure diagonal, from one corner of the sill to the other on both sides
  • If the diagonal measurements are not equal, you may want to switch to outside mounting


  • Measure the whole window, from the end of one frame to the end of the other
  • Add about 10 cms to each side for optimal light control
  • Measure the whole height, and again add about 10 cms

Measuring Windows for Blinds: Are You Ready? 

As you can see, measuring windows for blinds is easy-peasy. If you have any questions on this process, be sure to drop us a comment below. Or, maybe you’re still stuck on which blinds to choose for your home? We offer an obligation free consultation to assist with the measurements, blind choice and colours for you to pick the perfect option for your windows.