How Much Fabric for Curtains: Fullness, Widths and Repeats

How much fabric a pair of curtains needs comes down to four numbers: the track width, the fullness of the heading, the width of the fabric, and the finished drop. This guide sets out the calculation step by step, with a worked example for plain and patterned fabric, so an interior designer, architect or contractor can budget the quantity before the curtain maker confirms it. For KOTHEA’s curtain ranges and their widths, see our curtain fabric page. For contract fire standards and lining, see our contract curtain fabric specification guide.

Step 1: Fabric Width Needed Across the Track

Multiply the track or pole width by the fullness ratio for the heading. Fullness is the ratio of flat fabric width to finished curtain width, and it is what makes a curtain hang in folds rather than flat.

These are working figures. Heavier fabrics such as velvet often sit at the lower end, and the curtain maker may set a different ratio for a particular heading tape or track.

Step 2: Number of Fabric Widths

Divide the width needed by the width of the fabric, then round up to a whole number. Each width is called a drop or cut. For a pair of curtains, the widths are split between the two sides, so round up to an even number where the split would otherwise be uneven.

Fabric width makes a real difference. KOTHEA velvets are 135 to 140 cm wide, and KOTHEA handwoven linens run from 100 cm to 160 cm. The same window needs more cuts in a 100 cm fabric than in a 140 cm one. See our velvet upholstery fabric and handwoven linen fabric pages for the width of each range.

Step 3: Cut Length

Take the finished drop and add the allowances for the heading and the hem. A working allowance is 20 to 30 cm per cut, depending on the heading and the hem depth. The curtain maker will confirm the exact figure.

Step 4: Total Quantity, and the Pattern Repeat

For a plain fabric, multiply the number of widths by the cut length. That is the total in metres.

For a patterned fabric, each cut must start at the same point in the repeat so the pattern lines up across the seams. Add one full vertical repeat to each cut length for a straight match, and one and a half repeats for a half drop, then multiply by the number of widths. The full method is in our pattern matching guide.

Worked Example

A window with a 200 cm track, a pencil pleat heading at 2.5 times fullness, a finished drop of 250 cm, and a 140 cm wide fabric.

Linings and interlinings are calculated the same way, usually without a repeat allowance. For contract work, order the full quantity in one dye lot so every curtain in a scheme matches; see our lead times and dye lots guide. For upholstery quantities, see our how much fabric to upholster furniture guide, and for the full library our fabric buying guide by purpose.

Quick answers

How much fabric do I need for curtains?
Multiply the track width by the fullness ratio, divide by the fabric width and round up to get the number of widths, then multiply by the cut length (finished drop plus 20 to 30 cm for heading and hem). A 200 cm track at 2.5 fullness in 140 cm fabric with a 250 cm drop needs 4 widths of 2.8 m, or 11.2 m of plain fabric.

What fullness should curtains have?
Pencil pleat and pinch pleat headings usually take 2 to 2.5 times the track width, wave headings around 2.2 times, eyelet headings 1.5 to 2 times, and sheers up to 3 times. Heavier fabrics such as velvet often sit at the lower end of the range.

How much extra fabric do patterned curtains need?
Add one full vertical pattern repeat to each cut length for a straight match, and one and a half repeats for a half drop, then multiply by the number of widths. On the worked example in this guide, a 64 cm straight-match repeat raises the total from 11.2 m to 13.8 m.

Do contract curtains need Crib 5?
No. Crib 5 is the upholstery test in BS 5852. Contract curtains in the UK are specified to BS 5867 Part 2, usually Type B, or Type C where curtains are laundered repeatedly, as in healthcare. A Crib 5 certificate does not qualify a fabric for curtain use. See our BS 5867 Part 2 guide for the detail.

To request cuttings before ordering curtain fabric, visit KOTHEA.com/cuttings.