Curtain size calculator: length, rod height and panels

Curtains that stop short of the floor look like they expect a flood.

Measure the window, the gap above it and the ceiling height. We will tell you where to hang the rod, which stock length reaches the floor from there, and how many panels to buy.

Built from the size charts of Nicetown, Painting by the Penny and The Shade Store.

By the Sizemaven team. Rules checked against their sources October 2026.

Floral curtains framing a cottage window seat with green cushions and a view of fields — Photo: Rob Wingate on Unsplash

Find your size

Ceiling height

ftin

Floor to ceiling.

Window width

Outside edge to outside edge of the trim.

Window height

Top of the trim to the bottom of the sill.

Window top to ceiling

Top of the trim up to the ceiling.

Windows this size

windows

Where should the curtains end?

Pick sill or apron when a radiator, seat or counter sits under the window.

Fullness

Panel width

How the curtains open

Rod past each side of the window

Most you want to spend (optional)

Where to measure. Your answer is drawn here from your numbers.

1
Ceiling heightMeasure from the floor to the ceiling beside the window. If there is crown molding, measure to its bottom edge.
2
Window widthMeasure from the outside edge of the trim on one side to the outside edge on the other, not the glass.
3
Window heightMeasure from the top of the trim to the bottom of the sill or the trim under it.
4
Window top to ceilingMeasure from the top edge of the trim straight up to the ceiling. This is the room you have for the rod.

Curtain length chart

Our tool for floor-length panels, with the rod hung high as Nicetown and Painting by the Penny advise. Stock lengths from Graywind and Kwik-Hang.

Ceiling	Window top from floor	Rod height	Panel length
8 ft	80 in	14 in above, 2 in below ceiling	95 in, hem 1 in
8 ft	84 in	10 in above, 2 in below ceiling	95 in, hem 1 in
8 ft	88 in	6 in above, 2 in below ceiling	95 in, hem 1 in
9 ft	84 in	22 in above, 2 in below ceiling	108 in, hem 2 in
9 ft	96 in	10 in above, 2 in below ceiling	108 in, hem 2 in
10 ft	84 in	34 in above, 2 in below ceiling	120 in, hem 2 in
10 ft	96 in	22 in above, 2 in below ceiling	120 in, hem 2 in
10 ft	108 in	10 in above, 2 in below ceiling	120 in, hem 2 in
12 ft	96 in	25 in above, 23 in below ceiling	120 in

Curtain size guides

Questions about curtains

What length curtains do I need for an 8 ft ceiling?

Usually 95 or 96 inches, with the rod hung just below the ceiling. 84-inch panels reach the floor only when the rod sits just above a standard-height window.

How high should I hang a curtain rod?

High: designers hang it 2 to 6 inches below the ceiling so the window looks taller. If the panels you want are too short for that, hang it no lower than halfway between the window and the ceiling.

How wide should curtains be?

Together, the panels should be about twice as wide as the rod when laid flat. Use 1.5 times for a lighter look and 2.5 to 3 times for sheers.

How far past the window should the curtain rod go?

Most guides say 6 to 12 inches on each side, and some say 3 to 6. We use 8 inches so the open panels cover the wall rather than the glass.

What is the difference between floor, break and puddle length?

Floor length stops at or just above the floor. A break is 1 to 2 inches longer so the fabric bends at the floor. A puddle is 3 inches or more longer so the fabric pools on the floor.

How we size curtains

The rule comes from the charts below, checked October 2026. Brands differ, so check the size chart on the product page before you buy. Read our method