Whether you are a novice or an expert at interior decoration, our curtain size calculator will help you calculate the length and width of the curtain you need to buy to achieve your desired window treatment style.

Choosing the correct curtain size is not as easy as you may believe at first glance: personal taste, finance, style, and safety all influence the length and width of your window treatment. This curtain size calculator will simplify your job while providing all the necessary information to help you to make the right choice(s).

Before buying curtains, you need to measure your window to ensure that the result matches your vision. In this article, we will explore:

  • Standard curtain lengths.
  • The proper way to measure your windows for different window curtain styles.
  • The formula used to calculate the length and width of your window curtain.
  • How to achieve the correct finish for your curtain when it is too long.
  • Pitfalls to avoid when choosing curtains.

How to measure your window for different curtain styles

Whether looking for curtains for your new home or simply trying to achieve a new look for an old one, you must have the correct measurement before buying. The typical units used for curtains are inches or centimeters. It would be best to use either of these units when measuring your windows.

How to measure your window for different curtain styles.

Unless you want to hang your curtain significantly higher than the window, you should always measure from the top of the window frame to the point where you wish the curtain to stop. For long curtains, we typically measure to the floor. For short curtains, however, we measure:

  • From the top of the window to the top of the sill, for café and sill-length curtains.
  • From the top of the window to the bottom of the apron, for apron length curtains.

How to choose from the standard window curtain lengths

Curtains come in a variety of lengths as well as fullness. It is essential to know which of these you prefer before measuring your windows to calculate the size of curtain you will need. So what are the standard curtain sizes?

When we read about the standard curtain lengths, these sizes often only apply to long curtains. However, there are also shorter lengths.

The standard curtain sizes for long curtains measured in inches are 72, 84, 96, and 108.

Short window curtain styles are not used in homes nearly as extensively as long ones. We often use them for the area above sinks or radiators and in bathrooms or children's rooms. The standard curtain sizes for short curtains are 24 and 36 inches.

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How to calculate the length of your curtain using our curtain size calculator

Once you have measured your window, you should then enter the result in the height field of our curtain size calculator and choose your desired style from the type of curtain field. The calculator will then generate the correct length for you.

However, if you wish to understand how we do the calculations, the steps are outlined below. For the standard height, add 4 inches to the size to accommodate your rod's placement. For a room with a very high ceiling, 6 inches is better. If you are going for an exceptionally long curtain style that pools on the floor, we also add another 6 inches.

So for sill, apron, café, and floor-length curtains, we use the following formula:
Curtain length = Height + height of rod

For café length, we use:
Curtain length = Height/2

For extra long curtains, we use:
Curtain length = Height + height of rod + 6

💡 Please note: If you use centimeters to measure your windows, you must change the values in the formula to their appropriate conversion in centimeters. For instance, instead of adding 6, you would add 15.24 cm in the last equation.

How to find the correct width of your curtain from the standard curtain widths

To find the correct width of your window curtain, you should measure from the left outer edge of the window frame to the right. You may then enter this measurement in the window width field of our curtain size calculator. Next, choose the fullness you wish to have from the curtain fullness field, and our calculator will present you with the correct width.

The standard curtain width is always 2, 2.5, or 3 times the width of the window. So the formulas used to calculate the width of your curtain are:

  • Standard curtain width = width of window × 2.
  • Deluxe curtain width = width of window × 2.5
  • Ultra fullness = width of window × 3.

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What to do if your curtain is too long

Based on the style you are going for, your curtain can be as short as the top of the window sill, or it can pool on the floor. It is about personal taste and, to some extent, necessity. So if your measurement did not match any of the standard lengths and is a bit longer than you desire, do not worry you can easily remedy this by moving the window rod further up. You cannot go wrong with this since placing the window rod high above the window improves the room's look. You can go as far as to put it just below the ceiling to make your window appear taller.

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Are you looking for a curtain length or curtain width calculator?

If you wish to find either the curtain length or width, it is quite easy and does not require another tool. To find the curtain length fill the type of curtain and window height fields. To find the curtain width, on the other hand, use the curtain fullness and window width fields. No need to wait; the calculator will provide your answer in real-time.

Pitfalls to avoid when choosing from the typical curtain lengths

Long curtains should either stop at the floor, kiss the floor, or pool on the floor. Shorter than this, and you will lose the look of luxury and elegance. As a result, we must always ensure we have the correct size when looking at typical curtain lengths.

For areas with open fire or other types of heat, ensure you choose lengths that will keep your curtain above the place where the heat is. Additionally, short curtains make better choices for children's rooms and areas where the visually impaired or elderly reside to reduce the chance of accidents.


How do I calculate curtain length?

To determine the sill, apron, café, and floor-length curtain size, you can follow these steps:

  1. Measure from the top of the window frame to where you wish the curtain to stop.
  2. Add the height of the rod to the value determined in step 1.
  3. That's all! You have now calculated the desired curtain length.

How do I calculate curtain width?

If you want to determine the curtain width with standard fullness, you can follow these steps:

  1. Take the width of the window.
  2. Multiply the value noted above by two.
  3. That's all! You have now determined the curtain width according to the window's width.

How wide should my curtains be for an 84 inch window?

If you prefer standard curtain fullness, for an 84-inch window, you would require a 144-inch wide curtain.

To obtain precise measurements for the necessary curtain length and width, visit Omni's curtain size calculator.

What is the rule for curtain width?

How you choose the width of your curtains depends on the look you want to achieve and whether you prefer standard, deluxe, or ultra fullness in the curtain. Generally, The curtain width is always 2, 2.5, or 3 times the window's width.

Adena Benn
Type of curtain
Curtain fullness
Window height
Window width
Curtain length
Curtain width
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