Curtain Size Calculator
Determine the exact curtain width, length, and number of panels you need for perfect window treatments.
How to measure for curtains
Width: Measure the width of your curtain rod or track, not the window itself. The rod should ideally extend 4 to 8 inches beyond the window frame on both sides.
Length (Drop): Measure from the top of the rod (or from the eyelet rings) down to where you want the curtains to end (sill, apron, or floor).
Total Curtain Width Needed
Target Length: -- in
Panels Required
-- Panels
(Based on -- width)
Per-Panel Width
Each side (if split center) will need -- of fabric width.
Pro Tip: Always round up to the nearest whole panel. Having slightly more fullness looks much better than having curtains that stretch completely flat when closed.
How to Use This Calculator
- Enter Rod Width: Measure the total length of your curtain rod or track. If you haven't installed one yet, measure your window width and add 8 to 12 inches (20-30 cm) to allow the curtains to stack off the glass.
- Enter Drop Length: Measure from the rod down to your desired endpoint (the sill, just below the apron, or touching the floor).
- Select Fullness: Choose a fullness multiplier based on how rich and gathered you want the curtains to look when pulled entirely closed across the window.
- Panel Width: Enter the width of the pre-made panels you plan to buy (standard is often 50 inches or 130 cm), or leave it to calculate custom yardage needs.
- Calculate: Get your total required fabric width and the number of panels you need to purchase.
Curtain Sizing Rules of Thumb
Window treatments can make or break a room's design. Hanging curtains too low or buying panels that are too narrow are the two most common interior design mistakes. Properly sized curtains make ceilings look taller and windows look larger.
- Hang High and Wide: Install your curtain rod 4 to 6 inches above the window frame (or halfway between the frame and ceiling) to draw the eye up. Extend the rod 4 to 8 inches past the frame on each side so curtains don't block the light when open.
- The Golden Rule of Fullness: Curtains should never be pulled completely flat when closed. The total width of your curtain panels combined should be at least double the width of your window (2.0x fullness).
- Hitting the Floor: For a clean, modern look, curtains should just barely touch or "kiss" the floor (measure exactly to the floor). To prevent them from picking up dust, subtract 0.5 inches so they "float."
Understanding the Fullness Formula
"Fullness" is the ratio between the flat width of the curtain fabric and the width of the window rod it covers. This formula dictates how rich and gathered your drapes will look.
Total Fabric Width = Rod Width × Fullness Multiplier
Panels Needed = Total Fabric Width ÷ Single Panel Width
Choosing the Right Multiplier:
- 1.5x Multiplier (Minimal): Best for flat panel drapes or curtains that are primarily decorative and stay open.
- 2.0x Multiplier (Standard): The industry standard. Provides a classic, pleated look when closed. If your rod is 50 inches wide, you need 100 inches of total fabric.
- 2.5x to 3.0x Multiplier (Luxurious/Sheers): Best for lightweight fabrics like linen or sheers, which require intense gathering to look full and billowy. Also used for high-end pinch-pleat drapes.
Standard Ready-Made Curtain Drop Lengths
| Length (Inches) | Length (cm) | Typical Use Case |
|---|---|---|
| 63" | 160 cm | Sill or Apron length: Used for smaller windows, above radiators, or in kitchens. |
| 84" | 213 cm | Standard Floor length: Fits most modern standard ceilings (8-foot ceilings). |
| 95" or 96" | 241 cm | High Ceiling length: Used when hanging rods near the ceiling in 8 or 9-foot rooms to make them look taller. |
| 108" | 274 cm | Extra High Ceiling / Puddling: Used for 9-10 foot ceilings, or to create a romantic "puddled" effect on the floor. |
| 120" | 305 cm | Loft / Grand ceilings: Extra tall windows in formal rooms or lofts. |
Frequently Asked Questions
Does fullness apply to the curtain length as well?
No, fullness strictly refers to the horizontal width of the fabric required for proper window coverage. The length (or drop) of your curtain relies entirely on the height at which your rod or track is placed, and whether you want the fabric to touch the sill, float above the floor, or puddle on the ground in your room.
What is a "puddle" and how much extra length do I need?
Puddling is a styling choice where the curtains intentionally drag and pool on the floor, offering a very luxurious and romantic look for the room. For a slight break (like tailored pants), add 1-2 inches to your length. For a full puddle, add 6 to 8 inches to your floor-length measurement. Make sure to account for the bottom hem when calculating how much fabric to buy.
I calculated 2.3 panels. Do I buy 2 or 3?
When our calculator outputs a decimal, you should almost always round up to ensure the curtains provide the correct size and look full and plush when closed. In this case, you would round up to 3 panels. However, if you are doing a center-split draw, you must have an even number of panels for symmetry, so you would buy 4 panels (2 on each side).
How do I measure if I use ring clips?
If you are hanging curtains using rings with clips, measure the length starting from the bottom of the clip (the eyelet) down to the floor. The rings themselves will add about 1 to 2 inches of drop to the fabric. If you are using a different curtain header style (like grommets or a rod pocket), measure directly from the top of the rod.
How high above the window should I mount the curtain rod?
A general rule during installation is to mount the rod 4 to 6 inches above the top of the window frame. For a more dramatic look and to make ceilings appear higher, you can mount it halfway between the top of the window and the ceiling, or even closer to the ceiling line. Properly placed hardware enhances the dimensions of your space.
How far should the curtain rod extend past the window?
The curtain rod or track should extend about 4 to 8 inches beyond the window frame on each side. This allows the curtains to stack against the wall rather than blocking the glass and natural light when fully open, ensuring maximum window coverage.
What is the difference between total curtain width and panel width?
Total curtain width refers to the overall width of the fabric needed to cover your window with your desired fullness. Panel width is the specific measurement of a single piece of fabric (like a pre-made curtain you buy at a store). You usually need multiple panels combined to achieve the total curtain width required for your window's dimensions.
Can I use a 1.0x fullness multiplier?
While physically possible, a 1.0x multiplier means the fabric will be stretched completely flat across the window when closed. This is generally only used for flat panel shades or shower curtains, not traditional window drapes, as it looks very stark and lacks elegant folds. A higher fullness gives a much richer size and feel to the room.
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