Curtain size calculator: width, length and rod
Run the rod 6 to 12 inches past the window frame, hang it two-thirds of the way up to the ceiling, and buy panels totaling 1.5 to 2 times the rod width. A 48 inch window under an 8 ft ceiling takes a 60 inch rod at 92 inches and two 60 by 96 inch panels.
Updated · By the Interior Redesign AI editorial team · Sources cited on the page
Adding the extension to each side, and using the low end of each length range, are our readings of The Shade Store's guide.
2 panels to buy
60 in wide × 96 in
Finished drop 91.5 in; hem 4.5 in.
| Rod width (without finials) | 60 in |
|---|---|
| Rod height from the floor | 92 in |
| Rod above the window frame | 8 in |
| Total fabric width | 120 in |
| Width per panel | 60 in |
| Finished length from the top of the rod | 91.5 in |
| Ready-made length | 96 in |
Rings and clips lower the panel below the rod; check the heading on the product page before you buy.
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Key numbers
- Fullness
- Fabric width = rod width × 1.5 to 2; sheers about 2.5-3× (The Shade Store)
- Rod width
- Window plus about 6-12 in past the frame (The Shade Store)
- Rod height
- About two-thirds of the way from the window top to the ceiling (The Shade Store)
- Float length
- Rod to floor minus 1/4-1/2 in; break adds 1-2 in, puddle 3-6 in
- Ready-made lengths
- 63, 84, 96, 108, 120 in (The Shade Store)
Worked example
A 48 in window under an 8 ft ceiling
Window frame top at 84 in, ceiling at 96 in, floor-length curtains that float, 2× fullness, two panels.
- Rod width: 48 + 2 × 6 = 60 in.
- Rod height: 84 + (96 − 84) × 2/3 = 92 in, 8 in above the frame.
- Fabric: 60 × 2 = 120 in, so each of 2 panels is 60 in wide.
- Length: 92 − 0.5 = 91.5 in; the next ready-made length is 96 in (hem 4.5 in).
Buy two 60 in wide panels in 96 in length for a 60 in rod hung at 92 in.
How we calculate
Every rule comes from The Shade Store's measuring guide. The rod runs 6 to 12 in past the window frame; the guide does not say whether that is per side or in total, so we add your extension to each side (6 in by default, our reading of the guide; change it if your wall is tight).
The rod goes about two-thirds of the way from the top of the window to the ceiling, which makes the window look taller. You can type your own rod height instead.
Total fabric width is the rod width times the fullness, split across the panels: 1.5× looks tailored, 2× full, and sheers need about 2.5×. Length is measured from the top of the rod: float stops 0.5 in above the floor, break adds 1 in and puddle adds 3 in (the low end of each range, our choice), and sill length ends 1 in below the sill. Rings and clips add drop, so check the panel's heading before you buy.
We match the drop to the shortest ready-made length that is long enough (63, 84, 96, 108, 120 in) and show how much you would hem. Past 120 in, you need custom panels.
Estimates, sources
Planning estimates and published guidelines, not quotes, designs or code rulings. Figures were checked on each source on the date shown. Local prices, your home and your jurisdiction's adopted code decide the real answer.
- How to Measure for Curtains in 5 Steps (The Shade Store, as of Oct 26, 2026): fabric width = covered width or hardware span × 1.5 to 2 (sheers about 2.5-3×); rod about 6-12 in past the frame; rod about two-thirds of the way from the window top to the ceiling (8-10 in above the frame under cathedral ceilings); float = rod to floor minus 1/4-1/2 in, break = float + 1-2 in, puddle = float + 3-6 in, sill = to the sill or 1 in below; standard lengths 63, 84, 96, 108 and 120 in
Curtain length by ceiling height
Float length with the rod two-thirds of the way up, for a window whose frame top is 12 in below the ceiling, and the ready-made length to buy.
| Ceiling | Rod height | Float length | Buy |
|---|---|---|---|
| 8 ft | 92 in | 91.5 in | 96 in |
| 9 ft | 104 in | 103.5 in | 108 in |
| 10 ft | 116 in | 115.5 in | 120 in |
Sill, float, break or puddle
Pick the length by how the room is used, not only by looks.
- Sill: ends at the sill or 1 in below. Good over radiators, window seats and kitchen counters.
- Float: clears the floor by 1/4 to 1/2 in. Easiest to keep clean and the safest choice for most rooms.
- Break: 1 to 2 in longer than float, so the fabric bends slightly at the floor.
- Puddle: 3 to 6 in longer than float. Formal, but it collects dust and gets in the way of a vacuum.
How to use this tool
Measure the window
Width across the outside of the frame, and the floor to the top of the frame and to the sill.
Measure the ceiling
Floor to ceiling, so the rod can go two-thirds of the way up.
Pick fullness and length
1.5×, 2× or sheer, and sill, float, break or puddle.
Read the shopping list
Rod width and height, panel width and the ready-made length to buy.
Questions
How wide should curtains be?
1.5 to 2 times the rod width in total, split across the panels; sheers need about 2.5 times. A 60 in rod at 2× takes 120 in of fabric, two 60 in panels.
How far past the window should a curtain rod go?
About 6 to 12 in past the frame, per The Shade Store. We add it to each side, so the open curtains stack on the wall instead of over the glass.
How high should I hang curtains?
About two-thirds of the way from the top of the window to the ceiling. Under a cathedral ceiling, The Shade Store suggests 8 to 10 in above the frame.
What length curtains do I need for 8 ft ceilings?
With the rod two-thirds of the way up above a frame 12 in below the ceiling, the float length is about 91.5 in, so buy 96 in panels and hem them.
What are standard curtain lengths?
63, 84, 96, 108, 120 in. Buy the shortest length that reaches your drop and hem the rest.
Should curtains touch the floor?
Float length clears the floor by 1/4 to 1/2 in and suits most rooms. A break touches the floor by 1 to 2 in, and a puddle pools 3 to 6 in.
Numbers done. Now see it.
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