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Curtain Size Calculator
Estimate total curtain width, curtain drop, and optional width per panel from window size, fullness ratio, and allowances.
Enter your dimensions
Current unit: feet. The estimate updates automatically in your browser.
Enter the measured window width.
Enter the measured window height.
Enter the fullness multiplier for the curtain style, such as 1.5, 2, or 2.5.
Enter the extra length above the window for heading, rod position, or hanging style.
Enter the bottom hem or extra drop allowance.
Optional. Enter the number of curtain panels to estimate width per panel.
Estimated result
Total curtain width
Enter your inputs
Your estimate will appear here automatically once the required inputs are valid.
Guide
How to use this estimate
How the curtain size calculator works
This calculator multiplies window width by the fullness ratio to estimate total curtain width. It also adds the top allowance and bottom hem allowance to the window height to estimate curtain drop.
If you enter the number of panels, the calculator divides the total curtain width by that panel count to estimate width per panel. This is a sizing estimate, not a sewing pattern or fabric-yardage calculator.
What to measure
Measure the window width and window height. In imperial mode, enter these measurements in inches. In metric mode, enter them in centimeters.
Choose a fullness ratio based on the curtain style. A simple pair of curtains may use a lower fullness ratio, while sheers, pleats, wave curtains, or fuller decorative curtains may need more fabric width.
Example curtain size calculation
- Window width: 60 inches
- Window height: 72 inches
- Fullness ratio: 2
- Top allowance: 4 inches
- Bottom hem allowance: 8 inches
- Total curtain width: 60 × 2 = 120 inches
- Curtain drop: 72 + 4 + 8 = 84 inches
- With 2 panels: 120 ÷ 2 = 60 inches per panel
Estimated curtain sizing: 120 inches total curtain width, 84 inches curtain drop, and 60 inches per panel.
Quick reference
| Item | Value | Note |
|---|---|---|
| Width formula | window width × fullness ratio | This gives total curtain width across all panels. |
| Drop formula | window height + top allowance + bottom hem allowance | This estimates the finished curtain length or drop. |
| Panel formula | total curtain width ÷ number of panels | Only used when panel count is entered. |
Common mistakes to avoid
- Using window width as curtain width without applying fullness.
- Forgetting top allowance, rod position, heading style, or bottom hem allowance.
- Treating this as a fabric-yardage or sewing-pattern calculator.
Frequently asked questions
What fullness ratio should I use?
Fullness depends on curtain style and fabric. Simple curtains may use around 1.5× to 2× fullness, while sheers, pleats, wave curtains, or fuller decorative curtains may need more.
Is curtain drop the same as window height?
Not always. Curtain drop can include extra length above the window and extra length for hem, heading, rod position, or hanging style.
Does this calculate fabric yardage?
No. This calculator estimates finished curtain dimensions. Fabric yardage can also depend on fabric width, seams, lining, pattern repeat, pleats, and sewing method.