How To Measure for Blackout Curtains: A step by step guide – The Bedding Planet

How To Measure for Blackout Curtains: A step by step guide

This post is part of the blackout curtain buyers guide.

Blackout curtains are a worthwhile investment. They can cause you to have a more restful sleep by keeping light out of the room. They can also cut the cost of your utility bill by insulating the room. Blackout curtains help keep heat inside when it’s too cold and out of the house during the summer. This saves a lot on utility costs.

If you’ve finally decided you’d like to get blackout curtains, you’re probably wondering how to measure for them. This article contains a step-by-step guide to help you measure for blackout curtains.

Quick Guide to Measuring for Blackout Curtains

  1. Decide how you want to mount the curtains.
  2. Choose the curtain rod.
  3. If mounting on the outside of the window frame, extend beyond the window 2 to 3 inches on either side.
  4. If mounting on the inside of the window frame, mount the width of the window frame.
  5. Hang the curtain anywhere from 4 to 20 inches above the top of the window, depending on the aesthetic you’re going for.
  6. From the top position where the rod will be, measure to the bottom of where you want the curtains to hang. This would be either below sill level or floor length level for blackout curtains.

Read on to learn the mounting positions, how to choose the curtain rod, and the three different ways to hang your blackout curtains.

Decisions to Make Before Measuring For Blackout Curtains

Before even measuring your blackout curtains, you’ll need to know how you want to position (mount) the curtains. Will you want them on the inside of the window frame or the outside.

1. How To Position Them

One of the first things you want to do even before you start measuring is to decide whether you want to position the curtains outside or inside the window frame. Depending on the one you want, you get a different aesthetic.

Positioning Outside

Positioning the curtain on the outside is the most common style for hanging blackout curtains. When they’re outside, the rod is secured to the wall outside of the window frame.

This gives the perception that the window is larger and it provides full coverage to block out natural light. It also creates a more luxurious look. This is the best mounting position for your blackout curtains.

Positioning Inside

Positioning the curtain on the inside is not as common, but it does provide a certain look. With mounting on the inside, the curtain is secured inside the window frame.

This creates a more streamlined appearance. This does not completely block out light, but it does provide a modern, minimalist look. This is not the best positioning for blackout curtains

2. Curtain Rod

It’s best to choose the length of your curtain rod before you even measure your window for width. Curtain rods usually extend 3 to 6 inches past the window frame, because they can be installed either on the inside or the outside.

Determining where you install affects the length. It’s good to get a curtain rod that’s at least an inch thick for stability so it won’t bend in the middle.

Measuring Your Blackout Curtains

Outside Mount

Make sure the rod you use for the blackout curtains will extend beyond the window by about 2 or 3 inches on either side. Some curtains have a magnetic strip on the sides to hold them in place against the window frames.

Check your curtains to see if you have the magnetic strip. If they do, install a magnetic strip on the window frame to allow the strip to stick. This should not be easily seen with the naked eye, so try to make this as invisible as possible.

Inside Mount

The rod should only be as wide as the interior of the window frame. Opt for curtain rods with protective end caps and expandable design, as this will be a snug fit.

Top Mount

The first thing you want to do is ensure the rod for the curtains is above the top of the window. This will help block out as much light as possible. It’s ideal to extend about 4 inches up onto the window frame to keep the light out.

Depending on the overall look you’re going for, they could extend higher, about 6 to 12 inches above the window frame. Curtains can be hung as high as 20 inches above the window frame to create an elongated appearance.

The higher and wider your curtain rod, the larger your window will appear. Here’s an example of blackout curtains hanged at ceiling height:


From the top position of where the rod will be, measure to the bottom of where you want the curtains to hang. There are three ways to hang your curtains, depending on the look you’re going for. 

Above Sill: These curtains hang about 1 cm above the windowsill.

Below Sill: These curtains hang about 15 cm below the windowsill.

Floor Length: These curtains usually end 1 cm above the floor. 

You want to ensure your blackout curtains are indeed keeping light out, so measuring from the top to the below sill level or floor length level would be appropriate for your blackout curtains.

Blackout Curtain Buyers Guide Parts:

1. What Are Blackout Curtains And What Are They Used For?
2. Are Blackout Curtains Worth Getting? The Pros & Cons of Having a Dark Bedroom
3. What Are Blackout Curtains Made of? The Best Fabrics to go For!
4. Are Blackout Curtains Expensive? The 7 Best Priced Curtains of 2021
5. Are Blackout Curtains Energy Efficient? Can They Lower My Energy Bill?
6. What Color Should Blackout Curtains be in?
7. Blackout Curtains vs. Blackout Blinds: Which are better?
8. How To Measure for Blackout Curtains: A step by step guide
9. How To Clean Blackout Curtains: A step by step guide
10. Best Blackout Curtains For The Bedroom: A Buyers Guide (2021)

Niklas Lampi

My name is Niklas and I'm the author and content operator at The Bedding Planet. I've always had a big interest in bedding and more specifically sleep. If I find something that makes me sleep better, whether that's a lifestyle change or a better bedding environment, I'm ready to share it with the world!

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