Hang on. Measure first.

Curtain Size Calculator

Find the panels to buy and the rod position to plan. Count pairs, check fullness, and get a length that reaches.

Input

A plan before the curtain aisle.

Measure the window. Enter the panels you're considering. Filled-in sizes are examples, not retailer inventory.

Measurements

InchesCentimeters

Your window frame

Window width (in)Window height (in)

What about the rod?

Already installedPlan its placement

Usable rod span (in)Measure the span where fabric can hang; exclude decorative finials. The diagram assumes it is centered on the window.

Where should the curtains end?Finished endpointPanel top to desired endpoint (in)Measure from where the finished panel’s top will actually sit to your chosen endpoint near the floor. Include your desired gap in this measurement; nothing else is subtracted. Changing the endpoint clears this field so you can remeasure.

Fabric & the panels you can buyFullness multiplier2× means combined flat fabric width is twice the rod span. It is an editable choice within IKEA's pleating examples, not a universal requirement. Don't apply it again to an already pleated finished width.Flat width of one panel (in)Use one panel’s flat width, not the total printed on a pair package. Verify that the product is sold using flat-width measurements.Available panel length(s) (in)One length, or up to 12 separated by commas. Use a decimal point. The starting 84, 96 and 108 in are illustrative; replace them with actual options or leave blank for a target only. All options must share the width and packaging entered here.How are they packaged?Split panels evenly left and right

Even splits need an even panel count. If unchecked, no equal split is assumed; pair packaging may leave a spare.

Measurements, panel choices and results stay in this browser. Nothing is saved or added to the URL.

What's under the hood

How this tool thinks

Combined flat fabric width is usable rod span × your fullness multiplier. Divide by the flat width of one panel, round up, and use an even hanging count if you want the same number on each side. Pair packaging rounds the purchase separately; an unused spare does not count toward fullness.

A direct measurement from the panel's intended top to the desired endpoint takes priority. Otherwise, planned length combines rod height above the frame, window height, the chosen finish, and an explicit offset for the panel top relative to the rod. Positive offset means the panel top sits below the rod line, reducing the required length.

Available panel lengths come from you. We choose the shortest entered length that reaches; when none reaches, we show the shortfall and withhold a length recommendation. The extra length is a mathematical difference, not an allowance for sewing or shrinkage.

Pottery Barn's placement guidance supports editable 6-inch side/height choices and a 0.5-inch floor-gap option. IKEA describes different fullness ranges for different pleating; 2× is an editable starting choice. None of these defaults overrides the actual product's heading or measuring instructions.

Worth knowing

Useful in the real world

Measure the usable span where curtains can hang, excluding decorative rod finials. A rod narrower than the window is flagged; extra fullness cannot widen it.
Listings may describe one panel, a pair, a flat width or a finished pleated width. Confirm which you have before entering dimensions.
Rings, tabs, hooks and grommets can change where panel length starts. Prefer a direct finished-drop measurement with the actual hardware.
Open-stack width, center overlap, returns to the wall and blackout coverage are not included automatically. Check those with the chosen product.
Window handles, radiators, wall space and doors may limit placement. Follow the manufacturer's mounting and clearance instructions; the diagram does not establish safe anchoring.
No retailer stock is assumed. The filled-in 52-inch width and 84/96/108-inch lengths are editable examples. Puddles, fabric cutting and sewing instructions are outside this planner.

Try it on paper first

Worked examples

Real inputs, real outputs, and the assumption that changes the answer.

An installed 84-in rod

How many 52-in panels do I need at 2× fullness?

The target fabric width is 168 in. Three panels provide only 156 in, so 4 panels provide 208 in, or about 2.48× actual fullness. Buy 2 pair packages for an even split. For a measured 92-in drop and entered lengths 84/96/108 in, 96 in is the shortest that reaches, with 4 in to adjust.

Three panels mathematically, four to split

What changes on a 72-in rod?

At 2× fullness, 144 in of flat width needs 144 ÷ 52 ≈ 2.77 panels, rounded to 3 whole panels for width, or 4 for an even split. Four give about 2.89× fullness. Without the even-split request, two pair packages can supply 3 hanging panels and 1 spare; the hung fullness is then about 2.17×.

Planning the rod above a window

What finished length comes from a floor setup?

For a 60-in-wide × 60-in-high window, 6-in extensions make a 72-in rod span. With the rod 6 in above the frame, the frame's bottom 30 in above the floor, a 0.5-in floor gap and zero heading offset, target length is 95.5 in. Of 84/96/108 in, choose 96 in only if the 0.5-in excess can be adjusted as intended.

When no entered length reaches

Should I choose 84 in for a 92-in target?

If the only entered lengths are 63 and 84 in, the longer panel still stops 8 in short. The planner does not recommend it as a floor-length fit. Look for a longer option, or intentionally change and remeasure the setup.

Sill and apron targets

How does a shorter finish change the math?

A 48-in-high window with a rod 6 in above it and zero heading offset needs 54 in to reach the sill, or 58 in to reach an explicitly chosen point 4 in below it. That 4-in apron choice is an example preference, not a standard.

Receipts, where they matter

Sources & methodology

These sources support outside facts or conventions. The calculator's arithmetic and assumptions are still explained above.

How to Hang a Drape
Pottery Barn · manufacturer
Decorative guidance of 4–6 inches above the frame and 3–6 inches beyond each side supports the editable 6-inch placement defaults. Its half-inch-above-floor option supports the editable 0.5-inch floor-gap starting point. These are style choices, not installation requirements, structural advice or a guarantee that open curtains clear the glass.
Accessed 2026-08-30
Measure the window for curtain rails, rods or blinds
IKEA · manufacturer
Supports using rod span and desired pleating to estimate combined flat fabric width, with 1.5–2× and 2–2.5× example ranges, and measuring from the hanging position to the desired finish. The tool’s editable 2× starts within those ranges; suitability still depends on the product heading. It does not supply this tool’s illustrative panel sizes, package rounding or hardware offsets.
Accessed 2026-08-30

Short answers

Questions people actually ask

Does 2× fullness mean two panels?

No. It means the combined flat width of the fabric you hang is twice the rod span. Panel count also depends on each panel's width, whether you want an even split, and how packages are sold.

Should I choose the closest length, even if it is shorter?

A shorter panel cannot reach the entered endpoint in the same setup. This tool chooses the shortest entered length at least as long as the target, and shows any adjustment. It does not assume all products can be hemmed or altered.

How high and wide should I put the rod?

The starting choices are 6 inches above the measured frame and 6 inches beyond each side. They sit within the cited decorative guidance. Edit them for the actual window, fabric stack, available wall space and hardware instructions; they are not mounting rules.

What if my panels are already pleated?

Use this math only when the width is the flat fabric width. A finished pleated heading may already include fullness. Follow that manufacturer's coverage guidance instead of multiplying it again.