How to Measure Windows for Blinds

Window blinds can transform a room from boring to beautiful. However, you should measure your windows correctly to get the perfect fit. Measuring windows for blinds is pretty straightforward, and here’s a detailed guide to help you with it.


Table of Contents: 

  • What Are Window Blinds?
  • Measuring for Inside-Mount Blinds
  • Measuring for Outside-Mount Blinds
  • Tips to Measure Windows for Blinds
  • FAQs
  • The Final Word

First, What Are Window Blinds?

Window blinds are shades that control the amount of sunlight entering inside, increase your privacy, and enhance the appearance of your room. They are made of wood, metal, or composite and come in various styles. Window blinds are easy to clean and maintain.


If you’re looking for window blinds to enhance the appearance of your room, here are some of the best.

Measuring for Inside-Mount Blinds

Inside-mounted blinds sit inside the window frame and offer a cleaner look. If your windows have decorative moldings, these blinds should be your go-to choice because they won’t cover them up. Also, there will usually be enough depth to install the blind inside the window frame.


Here’s how to measure for inside-mount blinds: 


  • Width: Using a measuring tape, measure the inside of the window frame at the top, middle, and bottom. Take the smallest measurement for the width.
  • Height: Measure the inside of the window frame at the left, middle, and right. Take the longest measurement to ensure the window is completely covered. Even if your windows are not square or straight, measuring the width and height at three locations ensures the blind fits well.
  • Depth: Measure the depth of the window at the left, middle, and right sides. Take the smallest measurement for depth. The depth should be at least three inches to install inside-mounted blinds.

Measuring for Outside-Mount Blinds

Outside-mount blinds are installed directly on the wall outside the window frame. They don’t offer a flush look but cover the windows completely. If your window depth is shallow or your windows have large cranks or handles at the center, go for outside-mount blinds.


Here’s how to measure for outside-mount blinds: 


  • Determine headrail mount position: The mount should generally be three inches above the window frame.
  • Width: Measure from the outside edge of the left and right side frame. Add two inches on each side to ensure the window gets covered completely.
  • Height: Measure from the headrail mount position and add three inches below the window sill to block light completely.

Tips to Measure Windows for Blinds

Here are some tips to accurately measure your windows for blinds:


  • Use a steel tape measure for accurate readings.
  • Ensure the measuring tape is level when taking measurements. Even a slight tilt may affect the reading.
  • Measure the width first and then the height.
  • Measure twice to minimize the risk of errors.
  • Avoid estimating measurements. If you have doubts, measure again.
  • When replacing blinds, measure the window and not the blind.


Should I round up or down when measuring for blinds?

If you’re going for standard-size blinds, you may not get the exact size as your measurement. In this case, you can round down to the nearest ⅛-inch for inside-mounted blinds to ensure they fit within the window frame. Round up for outside-mounted blinds to ensure they cover the entire window.

How can I measure for blinds if my windows are not perfectly square?

Measure the width of the inside of the window frame at the top, middle, and bottom, and measure the left, middle, and right sides for height. Take the smallest measurement for inside-mounted blinds. Measure the width and height at the outside edge of the frame at multiple points and take the largest measurement for outside-mounted blinds.

How much overlap do I need for outside-mounted blinds?

Add two inches of overlap on each side and three inches at the top for complete coverage and privacy.

Should I hire a pro or install blinds myself?

Installing blinds is pretty straightforward. However, it takes time, especially if you have many windows to work on. If you want to spend your weekend with your family or simply don’t want to do the dirty work of measuring and drilling, hire a pro. Pros have the expertise to get the job done right the first time.

Which is better: standard or custom-made blinds?

Custom-made blinds are a better choice because every window is different. It usually takes two to four weeks for custom window blinds to be delivered. The time can vary depending on the manufacturer and your location. 

The Final Word

Measuring windows for blinds is a simple process. Follow the tips mentioned in this article to ensure the blinds fit perfectly and enhance the aesthetic appeal of your space. If you’re in San Diego county and need help choosing and installing the right window blind, get in touch with Family Interiors. With over 45 years of experience, our pros offer free in-house consultations and get the job done perfectly every time. Our reviews prove that!