Measure the window and the ceiling, pick the look. You get the rod, where to hang it, and the curtains to buy, in store sizes.
Curtains to buy
4 panels × 95″52″ wide, for a 48″ window under a 96″ ceiling
Quick answer: hang the rod high and wide: just under the ceiling (at least 4″ above the window frame) and 8–12″ past the frame on each side. Buy curtains that reach from the rod to about ½″ above the floor, in the nearest standard length (84″, 95″, 96″, 108″ or 120″). Buy enough panels that together they are about twice as wide as the rod. Under an 8 ft ceiling that usually means 95″ panels. The calculator above works it out for your window and tells you whether to hem or move the rod.
How to use the curtain size calculator
- Measure the window width from the outside edge of the trim on one side to the other. No trim? Measure the opening.
- Measure two heights from the floor: to the top of the window trim, and to the ceiling (or to the bottom of any crown molding).
- Pick the look: where the rod goes, how long the curtains are, and whether they hang from rings or clips (they sit about 1½″ lower) or straight on the rod through grommets or a rod pocket.
- Read what to buy: how many panels, which standard length, the rod length and which adjustable rod contains it, and the height to hang it. Copy link saves your numbers for the shop.
The rules the calculator uses
How high to hang curtains
The higher the rod, the taller the window and the ceiling look. That is why designers hang it just under the ceiling, leaving about 2″ for the brackets and finials. Never hang it lower than 4″ above the window frame; a rod sitting on the trim makes the window look short. “Halfway” is a middle ground: halfway between the top of the frame and the ceiling.
How wide the rod should be
Run the rod 8–12″ past the frame on each side. When the curtains are open they stack on the wall beside the glass instead of covering it, so you keep the light and the window looks wider. A 48″ window takes a rod of about 64–72″.
How wide the curtains should be
Flat, the panels together should be about twice the width of the rod (2× fullness). That gives soft folds when they are closed. 1.5× gives a flatter, more tailored look and 2.5× a lush one, which suits sheers. Panels are sold in pairs that meet in the middle, so the calculator always gives an even number of panels.
How long curtains should be
- Just above the floor (about ½″ clear): the cleanest look, and the one that stays clean and easy to vacuum around.
- Touching the floor: tailored, and it takes a precise measurement.
- A slight break of 1–2″ on the floor: relaxed, and it hides an uneven floor.
- Puddle, 6–8″ on the floor: romantic, for heavy fabric in a room nobody rushes through.
- To the sill (½″ above it) or below the sill (about 4″ past it): for kitchens, over a radiator, or behind furniture.
Standard curtain lengths, and when each one fits
Ready-made curtains come in a handful of lengths, so the answer is always one of these, plus a small adjustment: move the rod a few inches, or hem.
Curtain length by ceiling height
For a rod just under the ceiling, curtains just above the floor, window top at 84″:
| Ceiling | Rod height | Curtains to buy | Then |
|---|---|---|---|
| 8 ft (96″) | 94″ | 95″ | hem 1½″ |
| 9 ft (108″) | 106″ | 108″ | hem 2½″ (or 96″ with the rod 9½″ lower) |
| 10 ft (120″) | 118″ | 120″ | hem 2½″ |
How many curtain panels, and what size rod
With 52″ panels, 2× fullness and the rod 10″ past each side of the frame:
| Window width | Rod length | Adjustable rod to buy | Panels |
|---|---|---|---|
| 36″ | 56″ | 36–72″ | 2 |
| 48″ | 68″ | 36–72″ | 4 |
| 60″ | 80″ | 48–84″ | 4 |
| 72″ | 92″ | 66–120″ | 4 |
| 96″ | 116″ | 66–120″ | 4 |
| 120″ (slider) | 140″ | 84–144″ | 6 |
Three worked examples
A 48″ window under an 8 ft ceiling. The rod goes at 94″, 2″ under the ceiling, and runs 68″ wide. Curtains need to be 93½″ to float ½″ above the floor, so buy 95″ panels and hem 1½″. Four 52″ panels give generous folds on the 68″ rod.
The same window under a 9 ft ceiling. A rod at 106″ needs 105½″ curtains: buy 108″ and hem 2½″. If you would rather not hem, 96″ panels fit with the rod 9½″ lower, at 96½″. That still sits 12½″ above the frame, but it gives up some of the height.
A 36″ kitchen window, curtains to the sill. With the rod 4″ above a 60″ window top, the curtains need to be 27½″ long. The shortest standard length is 36″, so hem 8½″, or look for café-length panels.
Common curtain mistakes
- The rod on the window trim. It cuts the wall at its lowest point and makes the ceiling look lower. Go up.
- A rod exactly as wide as the window. Open curtains then cover part of the glass. Let them stack on the wall.
- One panel per side on a wide window. Stretched flat, they look like sheets. Aim for 2× the rod width.
- “High-water” curtains that stop a few inches above the floor. Either reach the floor or stop at the sill; the in-between reads as a mistake.
- Forgetting the rings. Rings and clips lower the curtain by about 1½″, and that is enough to turn a float into a drag.
Read next
- Curtain tricks designers use to make a room look larger
- Living room curtain ideas
- Beautiful curtains for a bedroom makeover
- How to layer blinds and curtains together
- Window treatments for a sliding glass door
Curtain size questions
How long should curtains be?
For most rooms, long enough to reach from the rod to about ½″ above the floor. Measure from where the curtain hangs (the rod, or the bottom of the rings) to the floor, then buy the nearest standard length and hem or move the rod to match. Kitchen and bathroom curtains often stop ½″ above the sill instead.
How high should you hang curtains?
As high as the wall allows: about 2″ below the ceiling or crown molding, and never less than 4″ above the window frame. The higher rod makes the window, and the room, look taller.
How wide should curtains be?
All the panels together should be about twice as wide as the rod (2× fullness), so they fall in soft folds when closed. The rod itself should run 8–12″ past the window frame on each side.
How many curtain panels do I need?
Multiply the rod length by 2 and divide by the width of one panel, then take the nearest even number, so the curtains meet in the middle. Only round down if that leaves you no more than about 15% short of the target. A 56″ rod with 52″ panels works out to 2.15, so one pair; a 68″ rod works out to 2.6, and one pair would be too flat, so four panels.
What size curtain rod do I need?
Window width plus 16–24″ (8–12″ on each side). Adjustable rods are sold by range, so a 68″ rod means buying a 36–72″ rod, and a 92″ rod a 66–120″ one.
What are the standard curtain lengths?
In the US: 63″, 84″, 95″ or 96″, 108″ and 120″, plus short 36″, 45″ and 54″ café lengths and 144″ for very tall rooms. 95″ and 96″ are the most common for 8 ft ceilings, 108″ for 9 ft, 120″ for 10 ft.
Should curtains touch the floor?
Floating about ½″ above it is the practical choice: it looks finished and stays clean. Touching, or a 1–2″ break, looks more relaxed. A puddle of 6–8″ is a deliberate, dramatic look for heavy fabric.
Planning the whole room? Draw it in the free 2D planner: windows, rug and furniture, all to scale.
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