Curtain Size Calculator

Selecting the right size curtains can dramatically transform a room, making it feel taller, wider, and more elegant. Conversely, ill-fitting curtains can make a space feel awkward and unfinished. The Curtain Size Calculator is a tool designed to help you determine the ideal length and width for your curtains based on your window dimensions and preferred interior design style. It takes the guesswork out of the process, ensuring you achieve a professional, well-proportioned look.

How to Use the Curtain Size Calculator

To find your recommended curtain dimensions, simply follow these steps:

1. Measure Window Width: Measure the width of your window frame in inches. For a more dramatic effect, interior designers often recommend installing the curtain rod 3-6 inches wider than the frame on each side. Enter the full width of the rod you plan to use.
2. Measure Window Height: Measure the height of your window frame in inches.
3. Select Length Style: Choose your desired curtain length from the dropdown menu. This determines where the curtains will end relative to the window sill and floor.
4. Select Width Fullness: Choose how full and gathered you want your curtains to be. This is a multiplier of your window width.

The calculator will then provide the recommended total width and length for your curtains.

Understanding the Calculations

The calculator uses standard interior design principles to determine the optimal sizes.

Curtain Width Formula

The total width of your curtain panels should be significantly wider than your window to create an aesthetically pleasing, gathered look when closed.

Recommended Total Width = Window/Rod Width × Fullness Factor

A fullness factor of 1.5x to 2.5x is standard. Our Curtain Panel Calculator can help you determine how many panels you need to achieve this width.

Curtain Length Formula

The length depends on the style you want to achieve. The rod is typically installed 4-6 inches above the window frame.

• To the Sill: The curtain just touches the windowsill. Length ≈ Window Height
• To the Apron: The curtain ends just below the bottom window trim (the apron). Length ≈ Window Height + 4 inches
• To the Floor: For a dramatic, elegant look, the curtain hangs to just above the floor. This requires measuring from the rod to the floor. Our calculator estimates this assuming the rod is a standard height above the window.

Practical Example

Let's assume you have a window with the following measurements and you want a full, floor-length look:

• Window Width: 72 inches
• Window Height: 60 inches
• Desired Length Style: To the Floor
• Desired Width Fullness: Full (2x)

1. Calculate Recommended Width:

Total Width = 72 inches × 2 = 144 inches

You would need a total of 144 inches of curtain fabric width (e.g., three 50-inch panels) to cover the window with a nice, full gather.

2. Calculate Recommended Length:

For a floor-length look, the rod would be mounted about 4-6 inches above the 60-inch window. Assuming a standard 8-foot ceiling (96 inches), the length from rod to floor would be calculated. The calculator estimates this to give a standard curtain length, often 84" or 96".

Why Curtain Size is Crucial for Interior Design

Hanging curtains high and wide is a classic designer trick. It creates an illusion of height and space, making your windows appear larger and the room grander. Curtains that are too short ("high-waters") can make a room look stunted, while curtains that aren't wide enough look flimsy and cheap. Using a calculator helps you avoid these common mistakes.

If you plan to sew your own curtains, our Fabric Calculator is an indispensable tool for estimating yardage. When shopping, you might need to convert units, where a Length Converter comes in handy.

For visual examples and further reading on window treatment best practices, home decor magazines like Good Housekeeping offer great inspiration. To learn about different fabric types, resources like The Spruce provide detailed guides.

Frequently Asked Questions (FAQ)

How high above the window should I hang the curtain rod?

A general rule of thumb is to mount the rod 4 to 6 inches above the window frame. This creates an illusion of height and makes the room feel taller.

How much wider than the window should the rod be?

Extending the rod 3 to 6 inches on each side of the window frame allows the panels to be pulled completely clear of the window when open, maximizing natural light.

What is the difference between "puddling" and "floor-length"?

"Floor-length" curtains typically hang about half an inch above the floor. "Puddling" is a more dramatic style where the curtains have an extra 1 to 6 inches of length that pools on the floor.