Curtain size calculator and window simulator
Measure the window. See it dressed. Get every number to order.
Enter four measurements. Get the rod, the panels, the length to order, how much daylight gets through, and the listings that can be bought or cut at that size. Add every window in the room for one shopping list.
Listings at your size
What can actually be bought, or cut, at these numbers
Ready-made panels come in fixed widths and a short list of lengths, so the calculator picks the nearest one and tells you where the hem will land. Made-to-measure listings are cut to your figures inside the merchant’s own configurator. Sizes, prices, fabric weights and opacity claims below are what each official listing published on the date shown, never a measurement of ours. Use Preview to dress the window above with a listing’s published light figure.
The spec sheet
Every number behind those sizes
The rod
Where it goes
The panels
How many, how wide
The length
What to order
Stack and light
What the open panels cover
Weight and hardware
What the rod has to carry
Ready-made or made to measure
Same window, two ways
Ready-made
Made to measure
The whole room
One shopping list for every window you added
Panel counts per listing, window by window. Ready-made figures use the nearest listed length; made-to-measure figures use the listing’s base price, which the merchant’s configurator then adds size, lining and options to. A starting point, never a quote.
Sewing them yourself
Fabric to buy, and what the finished panels will weigh
Cut lengths, widths per panel, total yardage for the active window and for the room. Hem and header allowances follow workroom convention: 8 in at the bottom for a double 4 in hem, 4 in at the top, 1.5 in side hems, 1 in lost at each join. Weights are arithmetic on a published fabric weight.
How the numbers are decided
Nothing here is a house secret. These are the working conventions of drapery workrooms, written down so you can overrule any of them. The long version, with the tolerances each brand publishes, is in how to measure for curtains. The wider set of measuring and installing decisions is in measuring, hanging and installing. The room presets above encode the same conventions per room: what a bedroom asks for is in curtains and drapes for bedrooms, a living room in curtains for a living room, and the short kitchen panel in cafe curtains compared.
Rod
- Overhang. The rod runs past the frame on each side so the open panels stack against the wall rather than over the glass: 4 in is the minimum that still reads as intentional, 8 in is the usual choice, 12 in on a window you want to look wider.
- Height. Standard mounting sets the rod 4 to 6 in above the trim. High mounting takes it to about 2 in below the ceiling, which draws the eye up. If there is less than 8 in between trim and ceiling, the calculator leaves 2 in for the brackets and goes as high as it can. The proportion question is covered in how high to hang curtains; what the rod itself needs is in curtain rods and hardware. Getting it on the wall, including the centre support a long span needs, is in how to put up a curtain rod.
- Stack-back. An open panel gathers to roughly a third of the width it covers at 2.5× fullness, proportionally less at 2× or 1.5×, and a little less on grommets. The calculator assumes about 2.5 in of trim between the frame edge and the glass, and tells you how much overhang would keep the glass clear. Stack-back decides the most on a wide opening, the case worked through in curtains for sliding glass doors.
Width
- Fullness. Total fabric width is the rod length times a multiplier: 2× for a normal gathered or pleated look, 2.5× for a denser fold and for sheers, 1.5× only for a flat, decorative pair that never closes. That total is divided by the number of panels.
- Ready-made widths. The ready-made listings verified for this page come in a single 50 in width or a single 100 in extra-wide width. The calculator counts how many of those add up to your total, and what fullness that count actually gives.
Length
- Measured from the rod, not the window. Grommet, rod-pocket and back-tab panels are measured from the top of the rod. Panels on rings or pin hooks hang from the ring eye, roughly 1.5 in below the rod, so that much comes off the length. Which header you choose, and what it hangs from, is in curtain hooks, rings and pins.
- Finish. Float is ½ in clear of the floor. Kiss touches. Puddle adds 4 in of fabric on the floor. Sill stops ½ in above the sill. Apron runs 4 in below it.
- Tolerance. Made-to-measure panels are cut by hand and the honest brands say so: Two Pages publishes a 1 in length variation, Neutral Curtains a 0.4 in tolerance on the finished size. If you want the hem to touch, order for a float and let the tolerance work in your favour. What else a made-to-measure order buys is in custom window treatments.
Weight and light
- Weight. Panel weight is the published fabric weight in grams per square metre times the panel’s area, using the finished width and the length plus about 10 in of hem and header. Lining adds its own published weight. What a lining is for beyond its weight is in thermal and insulating curtains. It is arithmetic, not a scale reading, and it excludes hooks, rings and buckram. Where the gsm figure comes from, and what it tells you before you order, is in how to choose curtain fabric.
- Light. The simulator uses a listing’s published opacity claim when it has one (a 20% sheer lets about 80% through, a 90% blackout about 10%). When a listing publishes no figure, the fabric look falls back to a category default and the note under the window says so. What those claims mean across blackout, room darkening and light filtering is in blackout, room darkening and light filtering.
Standard ready-made curtain sizes
Ready-made curtains are sold by length, in inches, and the list is short. Pick the length whose rod-top height matches yours, then check the width count from the calculator above.
| Length | Suits a rod top about | Typically used for |
|---|---|---|
| 63 in | sill or apron finish on a standard window | kitchens, bathrooms, café-style |
| 84 in | 84 in above the floor | rod just above the trim under an 8 ft ceiling |
| 96 in | 96 in above the floor | rod near the ceiling under 8 ft, or standard under 9 ft |
| 108 in | 108 in above the floor | 9 ft ceilings, rod mounted high |
| 120 in | 120 in above the floor | 10 ft ceilings |
Widths: 50 in per panel is the common ready-made width; 100 in extra-wide panels exist for large windows and sliding doors. Both are the widths carried by the ready-made listings verified on this page. Choosing between the lengths is covered in curtain lengths: 63, 84, 96 and how to choose, and the case for going made-to-measure in custom vs ready-made curtains.
Questions people ask
How wide should curtains be?
Two to two and a half times the rod length in total fabric, divided by the number of panels. A 64 in rod with a pair at 2× fullness needs 128 in of fabric, so two 64 in panels. Measure the rod, not the window: the rod already includes the overhang past the frame.
How long should curtains be?
Measure from the top of the rod (or from the ring eye if the panels hang on rings) down to where you want the hem: ½ in off the floor to float, on the floor to kiss, 4 in extra to puddle. Then read the brand’s tolerance before ordering, because a 1 in overrun turns a kissing hem into a puddle.
What are the standard curtain sizes?
Ready-made lengths run 63, 84, 96, 108 and 120 in. Widths are usually 50 in per panel, with 100 in extra-wide panels for large openings. Anything between those numbers is a made-to-measure order.
How high above the window should the rod go?
Four to six inches above the trim is the standard. Mounting just under the ceiling makes the window read taller and is the usual choice when the gap to the ceiling is small. Either way, extend the rod 4 to 12 in past the frame on each side so the open panels clear the glass.
How much fabric do I need to make curtains?
Add about 12 in to the finished length for hems and header, round that cut up to a whole pattern repeat, then count how many fabric widths each panel needs (finished width divided by the fabric width minus side hems). Cuts times cut length, divided by 36, is the yardage. The sewing section above does the arithmetic for your window and your fabric width.
How heavy are curtains, and does the rod matter?
A pair of 64 by 88 in panels in a 300 gsm velvet weighs about 5 lb of fabric before lining; the same pair in a 500 gsm cotton blend is closer to 9 lb, and a lining adds its own weight on top. Most rod listings publish no weight capacity at all, so check the one you buy; the only capacity published across the listings on this page is a motorised track rated at 110 lb.