Window Covering Installation Guide

Find out how to get the perfect measurements for your window coverings! Learn how to get accurate measurements for your blinds, roller and roman shades, and curtains in our ultimate window covering measurement guide.

Roller Shade Measurements

Roller shades are as simple as they sound! A wooden dowel or metal tube contains a swath of fabric that you can control by a spring or chain pulley system. These shades are a cost-effective way to completely transform your home and come in different fabrics and opacities. Sleek, simple, and stylish, roller shades are great for blocking out the sun while still letting the light in. 

Inside Mount:

  • Measure the depth of your window frame from the glass pane to the edge of where the frame sits out from the wall. 

  • Measure the width of the window at the top of the window only. 

  • Measure the height of your window in three places: left, centre, and right. Take note of the tallest measurement.


Outside Mount:

To determine the width: 

  • Measure the width of your window and add 1.5 in. to each side to determine the bracket-to-bracket width.
  • If your window has no trim, add 2 to 3 inches on each side to provide light gap coverage. 
To determine the length: 

Protruding Window Sill: Start at the sill and measure 3 in. above the top of the window to accommodate window hardware.

Flush Window Sill: Start 2 in. below the sill for maximum coverage and then measure 3 in. above the top of the window.


Roman Shades & Horizontal Blinds Measurements

Roman shades differ from rolling shades slightly: they stack up evenly like blinds when open but are completely smooth when closed. Their ease of use and variety of styles make them a popular choice among homeowners.

Horizontal blinds are more functional since they can emit different amounts of light through the slats. They also come in different widths, colours, and patterns. Remember to find blinds that are cordless, especially if you have pets! 

Roman shades and horizontal blinds are measured the same way.

Inside Mount:

  • Measure the depth of your window frame from the glass pane to the edge of where the frame sits out from the wall. 

  • Measure the width of the window at the top, middle, and bottom. Take note of the narrowest measurement. 

  • Measure the height of your window in three places – left, centre, and right. Take note of the tallest measurement. 


Outside Mount:

To determine the width: 

  • Measure the width of you window in three places – top, middle, bottom. 
  • If your window has no trim add 2 – 3 inches on each side of your window to provide light gap coverage. 
To determine the height: 

Protruding Window Sill: start at the sill and measure 3 in. above the top of the window opening to accommodate window hardware.

Flush Window Sill: Start 2 in. below the sill for maximum coverage and then measure 3 in. above the top of the window opening to accommodate for the window hardware.


Vertical Blinds Measurement

One of the most popular choices for sliding glass doors, vertical blinds are inexpensive and offer optimal light control. They come in a variety of materials including faux wood, fabric, or plastic. 

Inside Mount:

  • Measure the depth of your window frame from the glass pane to the edge of where the frame sits out from the wall, remembering to measure the door handle if there is one. 

  • Measure the width of the window at the top of the window only. 

  • Measure the height of your window in three places: left, centre, and right. Take note of the shortest measurement. 


Outside Mount:

To determine the width: 

  • Measure the width of your window and add 3 inches on each side to determine the bracket-to-bracket width.
  • If your window has no trim, add 3- 4 inches on each side of your window to provide light gap coverage. 
To determine the length: 

Protruding Window Sill: Start at the sill and measure 3 in. above the top of the window opening to accommodate window hardware.

Flush Window Sill: Start 2 in. below the sill for maximum coverage and then measure 3 in. above the top of the window opening to accommodate for the hardware.


Drapes & Curtains Measurements

Drapes and curtains provide the necessary sunlight coverage for your home. Perfect in almost every room, they also add a certain warmness to your home. They come in many different styles, from window length to pooling, drapes are the perfect addition to your window. 

To determine rod placement:

The placement of the rod will determine where the drapes or curtains lie. The standard placement is 6 in. above the window if the space allows for it. 

To determine the width: 

There are two types of curtains and drapes to consider before measuring: 

  • Side Panels: These are usually decorative are not meant to cover the entire window.  
  • Single Curtain Panels: These usually cover the entire window. 

Side Panels:

Measure the exact width you would like the panels to cover. Remember they can always be collapsed if you want to let more light in.

To determine length follow the same instructions as Single Curtain Panels. 


Single Curtain Panels:

  • Measure the width of the window opening from outside edge to outside edge of the window casing. 

  • Add 6 in. to each side. 

  • Divide the total number by the number of panels you want to order

To Determine the Length: 

Start out with this measurement and adjust according to your preferred style: 

  • Make a mark with a pencil where you will mount the brackets to your drapery rod.

  • Measure down to where you want to your drapes to hang. 

Record the measurements taken above and make the following adjustments depending on your style preference: 

Window Length: Measure from the brackets to ½ inch below your window sill. 

Sweep, Brushing or Cuff Length: Choose a length that is 1 to 3 inches longer than the recorded measurement. 

Floor Length: Choose a length that is 3/8 inches above the floor.

Pooling Length: Choose a length that is 6 to 12 inches longer than the recorded measurement.  


Measuring Window Coverings for Bay Windows

Bay windows are usually three panels that project outward from the main walls of the room. They give ample natural light to any room they’re in!

Measuring window coverings for bay windows can be tricky. Start by: 

  • Measuring i and iii: width side of the windows from the corners to the point you would like to cover. 
  • Measuring ii: width of the centre window from corner to corner
Measuring the Angles of a Bay Window:

To measure the angle of your bay window, you’ll need two business cards, a stapler, and a protractor.

The business cards are what you will measure to get the most accurate measurement. Start by setting two business cards on each corner angle of the windows, overlap them so they mimic the angle of the windows. Staple the overlapping business cards together so they stay in place. With a protractor: 

  • Measure the angle between windows i and ii
  • Measure the angle between windows ii and iii

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