Measure your window once and get everything you need to buy: how long the curtains should be for sill, floor or puddle length, how many panels for the fullness you want, the made-to-measure width and how long the rod must be.
Last updated:
Window (inches)
in
Outside edge to outside edge of the trim.
in
Top of the trim to the sill.
in
Rod mounting
in
4-12 in. Wider lets the open curtains clear the glass.
in
4-6 in standard; go higher (near the ceiling) to make the window look taller.
Curtains
in
Store panels are usually 50-54 in wide.
in
0 for grommet / rod pocket. Rings or clips: distance down to the ring eyelet (≈1.5-2 in).
Enter your values to see the result.
Advertisement
Advertisement
How to use the Curtain Size Calculator
Measure the window from trim edge to trim edge and from the top of the trim to the sill, plus the sill height from the floor.
Choose the mounting: outside mount with the rod extension and height above the frame, or inside the recess.
Pick the length style (sill to puddle) and how full you want the curtains.
Enter the panel width you plan to buy and any ring or clip drop.
Read the length, number of panels and rod size, and compare other fullness levels in the table.
Curtain size formulas
Rod width = window width + 2 × extension per side.
Total curtain width = rod width × fullness (1.5-3).
Number of panels = total width ÷ one panel's width, rounded up (to an even number for a pair).
Curtain length = rod height (or ring eyelet) − target bottom height. Floor length ends 1/2 in above the floor; a puddle ends 2-6 in below it.
Example: a 48 in window with 6 in extensions has a 60 in rod. At 2× fullness you need 120 in of curtain: 120 ÷ 52 = 2.3, so 4 panels (2 per side) in pairs. With the sill at 30 in, a 60 in window and the rod 6 in above the frame, the rod is 96 in from the floor and floor-length curtains are 95.5 in: buy 96 in panels.
Standard curtain lengths and where they end
Panel length
Typical use
63 in (160 cm)
Sill or below-sill curtains, small windows, kitchens
84 in (213 cm)
Floor length with the rod about 84 in high (standard 8 ft rooms, rod just above the window)
95-96 in (241-244 cm)
Floor length with the rod raised 6-12 in above the frame in an 8 ft room
108 in (274 cm)
9 ft ceilings or rods mounted near the ceiling
120 in (305 cm)
10 ft ceilings, two-story windows or puddled curtains
Fullness
Look
Best for
1.5×
Gentle waves, mostly flat
Heavy or patterned fabric, grommet panels
2×
Classic gathered look
Most curtains and drapes
2.5×
Full, tailored folds
Pinch pleat and ripplefold drapery
3×
Very full and soft
Sheers and voiles
Frequently asked questions
How wide should curtains be?
The combined width of all panels should be 1.5 to 3 times the rod length, with 2× being the standard for a nicely gathered look. For a 60 in rod at 2× fullness you need 120 in of curtain, which is three 52 in panels, or four if you buy them in matching pairs.
How long should curtains be?
Measure from the top of the rod (or the ring eyelet) to where the curtain should end: 1/2 in above the sill, 4 in below it, 1/2 in above the floor, touching the floor, or 2-6 in on the floor for a puddle. Floor length usually looks best in living rooms and bedrooms.
How far should a curtain rod extend past the window?
4 to 12 in on each side. The wider the extension, the more of the open curtain stacks over the wall instead of the glass, letting in more light and making the window look larger.
How high above the window should a curtain rod be?
4 to 6 in above the frame is standard. Hanging the rod higher, about halfway to the ceiling or just below the crown molding, makes the window and ceiling look taller; remember to buy longer curtains.
What are standard curtain lengths?
Ready-made panels typically come in 63, 84, 95 or 96, 108 and 120 in lengths. Pick the first length at or above your measurement and hem the extra, or use rings to fine-tune the height.
Does curtain length include the rings?
Ready-made curtain lengths are measured from the top of the grommet or rod pocket to the hem. If you hang them with rings or clips, the curtain hangs from the ring eyelet, so subtract that drop (usually 1.5-2 in) when working out the length.
How do I measure for inside-mount curtains?
Measure the width and height inside the window recess. The rod width equals the recess width, and sill-length curtains should be about 1/2 in shorter than the recess height so they clear the sill.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.