Curtain Fabric Calculator
Widths, drops and the cost of matching a pattern.
Calculate curtain fabric from track width, drop and fullness, including the widths needed and the extra a pattern repeat costs.
Leave at 0 for a plain fabric. A repeat rounds every drop up so the pattern matches across seams.
Fabric needed
8.50 yd
3 widths · 7.62 m
Lining roughly doubles the requirement but improves the hang and protects the face fabric from sun. Calculate it separately — lining has no pattern to match, so it needs no repeat allowance.
How the Curtain Fabric Calculator works
Curtains are a width problem before they are a length problem. The track length times the fullness gives the flat width the curtain must cover, and that divided by the bolt width gives how many drops to cut — each one the full finished length plus heading and hem. Then, if the fabric has a pattern, every drop after the first is rounded up to a whole repeat so the pattern matches across the seam, which is where the yardage quietly jumps.
Also known as: drapery fabric calculator · curtain yardage estimator
Width first, then length
A curtain is sized by the flat width of fabric it contains, not by the window. Multiply the track length by the fullness ratio — two is standard for a gathered heading — and that is the flat width the finished curtain must contain. Divide by the usable fabric width and round up to get the number of drops to cut.
Each drop is the finished length plus a heading allowance and a hem allowance, commonly eight inches each. Multiply the number of drops by the cut drop length and that is the fabric, before any pattern.
The order matters: because drops are whole widths, a track that needs 2.1 widths costs the same as one needing 3. Nudging the fullness slightly can sometimes save a whole width.
A worked example
A 60 inch track at 2x fullness needs 120 inches of flat width. On 54 inch fabric, with 53 usable, that is three widths. A finished drop of 84 inches plus eight for the heading and eight for the hem is a 100 inch cut drop. Three widths at 100 inches is 300 inches, or 8.33 yards.
Add a 24 inch pattern repeat and every drop rounds up to 120 inches — the next whole multiple of 24 above 100. Three drops at 120 is 360 inches, ten yards. The pattern has cost a yard and two thirds, and it costs it on every width, which is why a large repeat on a wide window gets expensive quickly.
Where the answer misleads
Fullness is a style decision that the calculator cannot make. Eyelet and flat headings look right at 1.5, pencil pleat needs 2.5 to hang properly, and a wave heading has its own requirement set by the track. Using the wrong fullness produces a curtain that is technically the right size and looks wrong.
Lining roughly doubles the fabric but is calculated separately, because it has no pattern repeat to match and is usually a narrower, cheaper cloth. It also changes the hem allowance, since lining is normally hemmed shorter than the face fabric.
Measure the track, not the window, and measure the drop from the track to where the curtain should finish — sill, below sill, or floor. A curtain calculated from the window is almost always too narrow, because tracks extend past the reveal on both sides.
Frequently asked questions
What fullness should curtains have?
Two times the track width is the usual minimum for a gathered heading, 2.5 for a fuller look and pencil pleat, and 1.5 only for a flat or eyelet heading where the pleats are structural rather than gathered.
How do I allow for a pattern repeat?
Round each cut drop up to a whole number of repeats. A 100 inch drop in a 24 inch repeat becomes 120 inches, and that extra 20 inches is paid on every width you cut, which on a three-width curtain is an extra 60 inches of fabric.
How much for heading and hem?
Eight inches each is a common allowance for a standard tape heading and a double hem, so 16 inches added to the finished drop. Formal curtains with a deep hem may want 12 inches at the bottom alone.
Should curtains be lined?
Lining roughly doubles the fabric requirement but improves how the curtain hangs, protects the face fabric from sun and helps with insulation and light. Calculate the lining separately, since it has no pattern repeat to match.