How to Calculate Fabric for a Curtain
To calculate the fabric for a curtain, multiply the rod width by a fullness ratio (1.5 to 2 for simple gathering tape, 2.5 to 3 for a fuller heading) to get the fabric width. For the height, measure from the top of the rod to the floor, then add the hems, usually 15 to 20 cm at the top and 10 to 15 cm at the bottom. Divide the fabric width by the roll width to find the number of widths (drops).
Calculating the fabric and sewing take time and precision. Kurtens makes curtains custom to the dimensions you give, delivered ready to hang, with no fabric calculation or cutting.
The 3 starting measurements
Three measurements form the basis of the calculation. Take them with a tape measure, rod fitted.
- Rod width, from one end to the other. It is the basis of the fabric-width calculation, not the window width.
- Desired height, from the top of the rod to the chosen bottom point: to the floor, just touching the floor, or to the window sill depending on the style.
- Roll width, the width of the fabric roll, often 140 cm. It determines the number of widths to join.
Calculate the fabric width
A curtain must be wider than the rod to hang in folds. You apply a fullness ratio to the rod width:
| Heading type | Ratio | Effect |
|---|---|---|
| Simple gathering tape, flat pleats | 1.5 to 2 | Light folds, understated |
| Eyelets, wave pleats | 2 to 2.5 | Regular folds, structured |
| Pleated heading, dense gather | 2.5 to 3 | Full folds, elegant |
Fabric width = rod width x ratio. For two curtains meeting in the centre, this total splits into two equal panels.
Calculate the fabric height
To the desired height, add the hems: count in general 15 to 20 cm at the top (for the heading and turn-over) and 10 to 15 cm at the bottom. Fabric height = desired height + top hem + bottom hem. If the fabric has a pattern repeat, add the height of one repeat per extra width.
Calculate the number of widths and the total fabric
Divide the required fabric width by the roll width (often 140 cm) and round up to the next width: that is the number of widths (drops) to sew side by side. Total fabric = number of widths x fabric height (hems included). Allow a small margin for pattern repeats and adjustments.
Example. A 200 cm rod, eyelet heading (ratio 2), desired height 250 cm. Fabric width = 200 x 2 = 400 cm, that is 3 widths in 140 cm roll width. Fabric height = 250 + 18 + 12 = 280 cm. Total fabric = 3 x 2.80 m = 8.40 m of fabric, excluding the repeat margin.
Skip the calculation: ready-to-hang custom
Calculating the fabric, buying it, cutting and sewing take time, equipment and precision: one mistake in the ratio or the hem and the drape is ruined. Custom removes this step. Kurtens makes curtains custom to the dimensions you give, in a range of colors and fabrics, delivered hemmed and ready to hang. You give your measurements, the curtain arrives finished. To take your measurements, see the measuring guide and the heading guide, then the Kurtens custom curtains.
Should a curtain be twice the width of the window?
No, not the window: the ratio applies to the width of the rod, overhang included. For home sewing, double suits eyelets; simple gathering tape needs 1.5 to 2, a pleated heading with dense gather 2.5 to 3. To order a Kurtens custom curtain, allow 2 to 2.5 times the rod width.
Starting from the window underestimates the fabric: since the rod is longer, the same width of fabric spreads over more space and forms thinner folds than planned. If there is no rod yet, measure the window, add the overhang you want on each side to get the length of the future rod, then apply the ratio.
How much fabric do you need for two curtains?
To sew them, calculate the fabric for the whole rod and divide it into two panels. With a 200 cm rod and a ratio of 2, allow 200 cm of fabric per panel. Three widths in 140 cm roll width, 2.80 m long, make 8.40 m, excluding pattern repeats, provided their width also covers seams and hems.
Each panel then gets one and a half widths: cut the third width in two lengthwise and sew one half to each full width. Each panel thus has 210 cm of fabric for the 200 cm needed; if those 10 cm are not enough for the joining seam and the side hems, plan two full widths per panel, that is 4 widths and 11.20 m of fabric, excluding any extra for pattern repeats.
What width should I enter when ordering a custom curtain?
For a Kurtens curtain, allow 2 to 2.5 times the width of the rod. For two panels meeting in the centre, divide that total in two: a 200 cm rod gives two panels of 200 to 250 cm each. For the height, enter the finished height you want, without a hem allowance: the curtain arrives hemmed.
With no rod fitted yet, start from the window: Kurtens recommends a rod that extends 15 cm beyond it on each side, so 30 cm more in total. A 200 cm window therefore calls for a 230 cm rod, and two panels of 230 to 288 cm each.
The ratio table above is for home sewing; for a Kurtens order, the rule stays 2 to 2.5 times the rod, and there are no widths to count and no roll width to check. The configurator accepts any size up to 1,000 cm wide for a height of 270 cm at most, or up to 270 cm wide for a height of 600 cm at most. It shows the price of the smallest size in its grid that covers your measurements, and the workshop receives your exact measurements. Beyond that, write to our team.
Frequently asked questions
What fullness ratio for a curtain?
Count 1.5 to 2 for a simple gathering tape with flat pleats, 2 to 2.5 for eyelets or wave pleats, 2.5 to 3 for a pleated heading with dense gather. The higher the ratio, the fuller the folds. It is applied to the rod width.
How to calculate the width of a curtain?
Multiply the rod width (not the window) by the chosen fullness ratio. A 200 cm rod with a ratio of 2 needs 400 cm of fabric in width, split into panels depending on the number of curtains.
How many metres of fabric for a curtain?
It depends on the rod width, the fullness ratio, the height and the roll width. For a 200 cm rod, eyelets and 250 cm height, count about 8.40 m in 140 cm roll width. Add a margin for pattern repeats.
What margin should you allow for curtain hems?
Count in general 15 to 20 cm at the top for the heading and turn-over, and 10 to 15 cm at the bottom for the hem. Add these margins to the desired height before calculating the total fabric.
How to avoid calculating the fabric for a curtain?
By ordering custom: you give the width, the height and the heading type, the curtain arrives hemmed and ready to hang, with no fabric buying or sewing. Custom to the dimensions you give avoids calculating the fabric.
Calculating the fabric takes precision; custom removes it. Have your curtain made to the right measurements as a Kurtens custom curtain, delivered ready to hang.
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