Curtain Size Calculator

How the Curtain Size Calculator Works

The Curtain Size Calculator is a handy tool designed to help homeowners and decorators find the ideal curtain dimensions based on their window measurements. By automatically calculating the proper width and length, it ensures full coverage and a polished, elegant look.

Whether you're planning a cozy living room or a sleek office space, this tool helps avoid common sizing mistakes, ensuring your curtains enhance both the aesthetic and function of the room.

Formulas Used to Calculate Curtain Size

The calculator uses two key formulas for determining ideal curtain dimensions:

• Curtain Width = Window Width × 2

• Curtain Length = Window Height × 1.0677

These formulas consider proper gathering for fullness and enough extra length for stylish floor draping or complete frame coverage.

Example:

• Window width: 120 cm

• Window height: 150 cm

Curtain width = 120 × 2 = 240 cm
Curtain length = 150 × 1.0677 ≈ 160.16 cm

This ensures the curtains not only cover the window but also provide the desired flow and volume.

Why should curtains be twice the window width?

Curtains are designed to be wider than the window to achieve:

• Natural gathering and pleating when closed

• Proper light blocking

• A richer and more elegant appearance

• Prevention of side gaps that let light through

A curtain that’s too narrow can look flat and fail to close fully, reducing both function and style.

How much longer should curtains be than the window height?

The added 6.77% ensures the curtain hangs just right. Depending on your style preference, this helps the curtain:

• Lightly touch the floor

• Cover the entire frame

• Puddle slightly for a luxurious effect (optional)

For floor-length curtains, a small 1–2 cm clearance is ideal to avoid dragging on the ground or gathering dust.

What if I want curtains above the window?

It’s recommended to install the curtain rod 15–20 cm above the window frame. This creates an illusion of taller ceilings and elongates the window visually.

Additionally, extend the rod 15–30 cm on each side of the window to:

• Let more natural light in when curtains are open

• Ensure the window is completely covered when curtains are closed

This enhances the room’s overall proportions and makes the window appear larger.

Curtain Size Reference Table

Here’s a quick guide to curtain dimensions based on window size:

This can help with planning multiple rooms or comparing fabric requirements.

How many curtain panels do I need?

Most curtain panels are sold in widths between 120–140 cm. Based on the total width calculated, you can decide:

• 2 panels for average windows (e.g., 240 cm total width)

• 3+ panels for wide openings or sliding doors

Ensure each panel is wide enough when drawn closed.

Tips for Installing Curtains Like a Pro

• Use double rods if layering with sheer curtains

• Choose grommets or hooks based on how often you’ll open/close them

• Iron or steam curtains before hanging to remove packaging creases

• Add tiebacks or holdbacks for daytime styling and light control

These small touches elevate the room’s look and make curtains more functional.

What fabric should I choose?

The type of fabric affects how the curtain falls and filters light:

• Linen or cotton: Great for airy, casual settings

• Velvet or blackout: Best for blocking light and adding insulation

• Silk or faux silk: Offers elegance with soft draping

• Sheer fabrics: Ideal for privacy with daylight filtering

Choose fabric based on your room’s purpose and style.