Curtain Size Calculator — What Size Curtains Do I Need?

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Curtain Size Calculator — What Size Curtains Do I Need?

CurtainsFree toolLast updated: March 26, 2026
For a standard 48-inch wide window, you need curtains with a total width of 96 inches (2× fullness ratio) — that’s two 50-inch panels. Mount the rod 4–6 inches above the window frame and extend it 6 inches past each side for a professional look. Enter your window measurements below for exact panel size, rod width, and the closest ready-made curtain size you can buy off the shelf.
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per panel
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panel length
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panels needed
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rod width
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Window measurements
Style
Rod placement (defaults: 4" above, 6" extension)
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Ready-made size match
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Curtain panels
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Curtain rod
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Rod brackets
Standard pair
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What size curtains do I need for my window?

The width of your curtains should be 1.5 to 2.5 times the width of your curtain rod — not the window itself. This extra fabric creates the fullness (pleats and gathers) that gives curtains a professional, designer look. According to the Window Covering Association of America (WCAA), 2× fullness is the industry standard for most heading types. For a 48-inch window with a 60-inch rod (6-inch extensions on each side), you need 120 inches of total curtain width — typically two 50-inch or two 52-inch panels.

For length, the golden rule is to mount your curtain rod 4 to 6 inches above the window frame and let the curtains hang to approximately ½ inch above the floor. This creates the illusion of taller windows and higher ceilings. Curtains that stop short of the floor by more than 2 inches look unfinished; curtains that puddle on the floor (6+ inches of extra fabric) create a luxurious, dramatic look best suited for formal rooms.

How wide should curtains be for each window size?

The formula is simple: rod width × fullness ratio ÷ number of panels = panel width. For a standard 48-inch window with 6-inch rod extensions (60-inch rod) at 2× fullness, total width is 120 inches. Divided by 2 panels, each panel should be 60 inches wide. The closest ready-made panel width is 52 inches (standard at Target, IKEA, and Amazon) or 50 inches — two panels of either size will provide adequate fullness. For formal rooms, increase to 2.5× fullness. For casual or modern spaces, 1.5× works well with grommet and tab-top headings.

How high should I hang my curtain rod?

Interior designers recommend mounting the curtain rod 4 to 6 inches above the top of the window frame. For rooms with 8-foot ceilings, 4 inches above the frame is standard. For rooms with 9 or 10-foot ceilings, go higher — up to 6 inches above the frame or even at ceiling level for a dramatic effect. Hanging the rod higher makes the window appear taller and the ceiling appear higher. The rod should extend 3 to 8 inches beyond the window frame on each side (6 inches is the most common) so curtains can stack off the glass when open, maximizing natural light.

Standard curtain sizes at major retailers

Ready-made curtains in the US come in standard lengths of 24, 36, 63, 84, 95/96, 108, and 120 inches. The 24-inch and 36-inch sizes are tier/café curtains for kitchen windows and bathrooms. Standard panel widths are typically 42, 50, 52, or 54 inches. If your calculated length falls between sizes, always buy the next longer size and hem to fit — it is much easier to shorten curtains than to add length. Most retailers including Target, Amazon, IKEA, Pottery Barn, and West Elm carry these standard sizes.

Frequently asked questions

What size curtains for a 72-inch window?
With a 72-inch window and 6-inch rod extensions (84-inch rod), at 2× fullness you need 168 inches total width. That’s 4 panels at 42 inches each (2 per side). Search for “42 inch curtain panels 84 inch length” for ready-made options.
What size curtains for a 36-inch window?
With a 36-inch window and 6-inch extensions (48-inch rod), at 2× fullness you need 96 inches total. Two standard 50-inch panels provide 100 inches — a perfect match. This is the most common bedroom window size.
Should curtains touch the floor?
For the most polished look, curtains should hover ½ inch above the floor. This prevents dust collection while maintaining an elegant appearance. Curtains that stop 2+ inches above the floor look unfinished. For dramatic effect, let curtains puddle 6–8 inches on the floor.
How many curtain panels do I need?
For windows up to 60 inches wide: 2 panels (one per side). For windows 60–96 inches: 4 panels (two per side). For sliding doors and windows over 96 inches: 6 panels (three per side). Total curtain width should be 2× the rod width.
What is curtain fullness and which should I choose?
Fullness is the ratio of total curtain fabric width to rod width. 1.5× creates a casual modern look. 2× is the WCAA industry standard with attractive pleats. 2.5× creates formal, luxurious gathers. 3× is for sheer fabrics that need extra volume.
How far should the curtain rod extend past the window?
Extend the rod 3 to 8 inches past each side of the window frame. The standard is 6 inches. This allows curtain panels to stack off the glass when open, maximizing natural light and making the window appear wider.
What are café curtains?
Café curtains cover only the lower half of a window, hung from a tension rod at the midpoint of the window frame. They’re popular for kitchens and bathrooms because they provide privacy while allowing light through the upper half. Standard café lengths are 24 and 36 inches.
Calculations based on WCAA (Window Covering Association of America) standards and professional interior design guidelines. Ready-made sizes reflect 2026 US retail standards. For non-standard windows (bay, arched, corner), consult a window treatment professional.