Curtain Calculator
Work out how long and how wide your curtains should be, how many panels to buy, and where to hang the rod, all from a few window measurements.
Window
Outside edge to outside edge of the trim.
8 ft = 96 in, 9 ft = 108 in.
Rod Placement
4–10 in lets open panels clear the glass.
Most ready-made panels are 50–54 in wide.
Fullness
Length Style
Your Curtain Size Will Appear Here
Enter your window measurements and preferences, then click “Calculate Curtain Size.”
Curtains & Hardware Worth a Look
Hand-picked products to help you get the best results on your project.
Linen blend
Linen-Look Curtain Panels, 95 in
- ✓Soft, relaxed texture
- ✓Filters light without blocking it
- ✓Fits most 8 ft ceilings
Blackout
Blackout Curtain Panels, 108 in
- ✓Blocks morning light
- ✓Adds insulation
- ✓Long enough for high rods
Curtain rod
Adjustable Curtain Rod, 48–144 in
- ✓Extends well past the frame
- ✓Center support bracket
- ✓Sturdy for heavy panels
Clip rings
Curtain Clip Rings
- ✓Smooth open and close
- ✓Hang panels at any height
- ✓Easy fix for slightly long panels
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How to Measure Your Window
Step 1: Window Width
Measure from the outside edge of the trim on one side to the outside edge on the other. No trim? Measure the opening.
Step 2: Frame Height
Measure from the floor to the top of the window frame, then measure the ceiling height. Measure in a couple of places; older floors aren't always level.
Step 3: Pick Your Look
Choose standard or high rod placement, how far the rod extends, how full the curtains should be, and whether they float, kiss or puddle.
Standard Curtain Lengths
| Panel length | Usually fits |
|---|---|
| 63 in | Short windows and sills; rarely right for floor-length looks |
| 84 in | Rod mounted right at the top of a low window frame |
| 95 in | Standard 8 ft ceilings with the rod a few inches above the frame |
| 108 in | Rods mounted high on 8–9 ft ceilings |
| 120 in | Rods near the ceiling on 9–10 ft ceilings |
If you land between two sizes, buy the longer one and hem it, or raise the rod slightly. Clip rings lower a panel by about an inch.
A Worked Example
A 48 in wide window with the top of the frame 84 in above the floor, an 8 ft ceiling, the rod 5 in above the frame, 6 in of rod past each side, 2× fullness, 50 in panels, and a “kiss” length:
- Rod length: 48 + 6 + 6 = 60 in
- Total panel width: 60 × 2 = 120 in → 120 ÷ 50 = 2.4 → 4 panels (rounded up to pairs)
- Rod height: 84 + 5 = 89 in, so the curtains need to be 89 in long
- Buy 95 in panels and hem 6 in, or raise the rod
Want the reasoning behind each rule? Read how long curtains should be.
Frequently Asked Questions
For most rooms, curtains should reach the floor: either floating about half an inch above it or just touching it. Measure from the curtain rod to the floor, then add 1 to 2 inches for a slight break or 4 to 8 inches for a puddle look.
Mount the rod at least 4 to 6 inches above the window frame. For a taller-looking room, go about halfway between the top of the frame and the ceiling. Just remember that a higher rod needs longer panels.
The total width of all your panels should be about 2 times the length of the rod for a standard look, 1.5 times for light sheers, and 2.5 times for a full, luxurious look. Too little fullness makes curtains look flat when closed.
Extend the rod 4 to 10 inches past each side of the window frame. That lets the open panels stack on the wall instead of over the glass, which lets in more light and makes the window look wider.
With a rod mounted about 5 inches above a standard 84-inch-high window frame, you need about 89 inches, so 95-inch panels hemmed slightly (or hung with clip rings) usually work best. 84-inch panels typically end up too short on a standard window.