Curtain Size Calculator

What is a Curtain Size Calculator?

A curtain size calculator helps you determine the correct length and width of curtains for your windows. By entering your window measurements and choosing your preferred curtain style and fullness, you get precise curtain dimensions that help you buy ready-made curtains with confidence.

Whether you want sill-length curtains for the kitchen, floor-length drapes for the living room, or extra-long curtains that pool elegantly on the floor, this calculator adjusts the length calculation for each style and accounts for rod placement and fullness preferences.

How to Measure Your Windows for Curtains

Accurate window measurements are the foundation of well-fitting curtains. Follow this guide:

• Measure the height: Measure from the top of the window frame to where you want the curtain to end. For floor-length curtains, measure to the floor. For sill-length, measure to the window sill. For apron-length, measure to just below the sill.
• Measure the width: Measure from the left outer edge of the window frame to the right outer edge.
• Decide on rod placement: Standard placement is 4 inches above the window frame. For rooms with high ceilings, 6 inches is recommended to make the window appear taller.
• Choose your fullness: Standard fullness (2x) works for most windows. Deluxe (2.5x) and Ultra (3x) create more dramatic, gathered looks.

Standard Curtain Sizes

Ready-made curtains typically come in standard lengths. The most common sizes are:

• Long curtains: 72", 84", 96", and 108" — for floor-length and puddling styles.
• Short curtains: 24" and 36" — for café, sill, and apron styles.

Use this calculator to find out which standard size is closest to your needs, or get the exact custom measurement for made-to-order curtains.

How the Calculation Works

The curtain length is calculated based on your chosen style:

• Sill, Apron, and Floor Length: Curtain length = window height + rod height above window.
• Cafe Length: Curtain length = window height / 2 — covers the bottom half of the window.
• Extra Long (Pools on floor): Curtain length = window height + rod height + 6" — the extra length creates a elegant pooling effect on the floor.

The curtain width is calculated by multiplying the window width by your chosen fullness factor: 2x for standard, 2.5x for deluxe, or 3x for ultra fullness. This ensures the curtains look full and luxurious even when closed.

Need help with other home projects? Try the Curtain Panel Calculator for sewing your own curtains or the Tablecloth Size Calculator for dining room decor.