How Long & Wide Should Blackout Curtains Be? (Solved)

Blackout curtains are designed to block out all light and to make the room completely dark. These curtains are made to mimic a dark and cave-like feel in a room, which is good for sleeping or relaxing, even during the day.

Basically, blackout curtains should be longer than the height of the window and wider than the entire width.

Here is how long and wide blackout curtains should be:

In general, blackout curtains should just be wider than the window frame. This is to ensure that no light can enter from the sides of the curtains. Blackout curtains should also be longer than the windows. This is to prevent any light from entering from the bottom of the curtains.

How Much Should Blackout Curtains Overlap?

Blackout curtains should overlap. This is to ensure that there are no small gaps for light to enter the room.

When not in use, blackout curtains are expected to be open during the day. So as a general rule, there should be an overlap of at least four inches for your blackout curtains.

This means that the curtain rod should extend at least four inches from the edge of the window frame. This will give you enough allowance for your curtains to drape nicely during the day.

When the curtains need to be closed, the overlap ensures that there would be no gaps that can let light in.

How Long Should Blackout Curtains Be?

Blackout curtains should be long enough to reach the floor.

This is to not let any amount of light in so that you could make the room completely dark.

Here is how to get the right measurement for how long your blackout curtains should be:

  1. From the top of the window frame, measure at least 4 inches. This is where your curtain rod will be. If the distance between the window frame and the ceiling is 12 inches or more, or if you want the illusion of a higher ceiling, you should place the curtain rod higher.
  2. Measure the length of your windows on both sides, and take note of whichever is the longer measurement. This will be your base window length.
  3. Then measure from the top of the window frame to where the curtain rod will be. Add this number to the base window length, and then add 5 to 8 inches. The final number is how long your curtains will be.

The resulting number will be the right length so that your blackout curtains can completely cover your windows from top to bottom. Anything shorter than this may not be ideal as it can light some light in.

The longer your blackout curtains are, the better they will be for blocking light.

This means that if you have the budget for floor-length or floor-to-ceiling curtains, it is highly recommended that you choose them. They may be pricey because they use up more material, but they are definitely worth it.

How Wide Should Blackout Curtains Be?

Blackout curtains should be wider than your windows to make sure that no light enters from the sides of the window.

Here is how to get the right width for your blackout curtains:

  1. Measure the width of your window frame. Start from the one outside edge of the window frame to the other. This will be the base window width.
  2. Add 25 percent of the base window width to the measurement. This is how wide your window should be. For example, if the base width of the window is 100 inches, the width of the blackout curtains should be 125 inches.

Anything less than the recommended width can risk letting some light in through the sides.

So it is always best to measure your windows to get the right size of blackout curtains for your room.

Do Blackout Curtains Need to Cover the Entire Window?

Since the purpose of blackout curtains is to block all light and to make the room completely dark, blackout curtains need to cover the entire window.

It also needs to cover the small area around the edges of the window.

Having blackout curtains that properly cover the entire window lets you maximize the functionality of these curtains, so you get the full blackout effect in your room.

Can You Get Blackout Curtains for Sliding Glass Doors?

Blackout curtains are not only used for windows. They can also be used for sliding glass doors.

Sliding glass doors can let a lot of light in so if you want to make a room dark even if you have sliding glass doors, then you can install blackout curtains to fit it.

This is a good idea if you want to make the room multi-functional.

The sliding glass doors let light in during the day so get to be more productive.

And when it is time to relax or take a nap, you can close the blackout curtains on these glass doors so you can convert the room into a space that is good for napping.

Floor-to-ceiling blackout curtains are recommended for this.

Sliding glass doors may be too big for ready-made blackout curtains but there are lots of stores that can customize curtains big enough to cover the entire door.

Can Blackout Curtains Keep out ALL Sunlight?

Blackout curtains can keep out all sunlight when installed properly.

Good quality blackout curtains really do work. These curtains are very effective and can completely keep out all sunlight from entering the room.

Blackout curtains have a three-pass lining technology which ensures that light does not enter. These curtains are made of three layers of lining and fabric.

These curtains are normally made of thick and heavy fabric that is tightly woven so light does not pass through.

This fabric is the layer that faces the room.

Linings are then added to the fabric, which is an essential part of blackout curtains. These curtains normally have three linings. This is made by attaching a layer of white foam to the back of the curtain fabric. Then a black lining is added and then followed by another layer of white.

The white layers are made to prevent the black lining from messing up the decorative aspect of the fabric, while the black layer works to block the light and help retain the heat.

This is what makes blackout curtains very effective.

Blackout curtains are the best window treatments you can get if you want to make your room completely dark.

Just remember to take proper measurements of your window so you can choose one that covers and overlaps the entire window, so you can maximize the curtain’s functionality.


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