To calculate curtain fabric yardage, multiply your track or pole width by your fullness ratio (typically 2 to 2.5 times the track width), divide that total by the width of the fabric on the roll, and round up to the next whole number of fabric widths; multiply that width count by your finished drop plus a hem and heading allowance to get the total yardage, then add about 10% extra to cover pattern matching, shrinkage and cutting mistakes.
Yardage is one of those things that is almost always overshot by hand. Curtains have to be gathered to look right, which means a 240 cm (about 94 in) track at double fullness needs roughly 480 cm of flat fabric spread across multiple widths. If the fabric comes off a 54 in (137 cm) roll, that is 480 ÷ 137, which works out to roughly 3.5 widths — and because you cannot buy half a width, you round up to 4. Three widths would leave the curtain too flat to pleat properly. The cut length is your finished drop from hook to hem plus the turnings at the top and bottom, and the total yardage is just widths multiplied by that cut length. Getting any one of these three numbers wrong throws the whole order off, which is exactly why the Curtain Fabric Calculator runs all three steps live as you type.
The Three Numbers Behind Every Yardage Estimate
Every curtain yardage calculation, no matter how complicated the window or how many panels you are sewing, comes down to three numbers: the number of fabric widths to cut, the cut length of each width, and the total fabric to buy. The widths are almost always the figure that trips people up.
Start with your track or pole width. That is the visible width the curtain has to span when drawn closed. Multiply it by your fullness ratio to find the flat fabric width the curtain needs to gather down to the pole. Divide that flat fabric width by the width of the fabric on the roll, then round up to the next whole number. The result is how many fabric widths, or drops, you cut.
The cut length is more straightforward. Measure from the hook or track down to where you want the hem to fall. That is your finished drop. Add your hem and heading allowance on top — the fabric folded under at the top for the heading tape and folded under at the bottom for the double hem. A common combined allowance is 20 to 25 cm, about 8 to 10 in, but use the value that matches your heading tape and hem style.
The total is simply widths times cut length. After that, add about 10% extra for pattern matching, shrinkage and cutting mistakes, and you have a safe number to order.
Fullness Ratios by Heading Style
Fullness is a matter of look and heading, and choosing the right ratio is half the job. A curtain that is barely gathered looks thin and mean; one that is heavily gathered looks generous but heavy. The table below covers the ranges the calculator exposes and the headings they suit.
| Heading style | Typical fullness ratio | Best for |
|---|---|---|
| Pencil pleat | 2.0× to 2.5× | Most domestic curtains, versatile look |
| Pinch pleat (double or triple) | 2.0× to 2.5× | Formal rooms, lined curtains |
| Eyelet | 1.5× to 2.0× | Modern look, lighter fabrics |
Below 1.5× the curtain looks flat and skimpy; above 2.5× it is very full and heavy. The 2× default sits in the middle of the usual range and is the right starting point if you have no reason to choose otherwise.
How to Use the Curtain Fabric Calculator
The calculator handles the three numbers above plus the +10% safety margin in one go. To get a yardage estimate without doing the arithmetic yourself:
- Pick your units (inches or centimetres), then enter the track or pole width, the finished curtain drop, your fullness ratio, and the width of your fabric off the roll.
- Set the hem and heading allowance — 20 to 25 cm or 8 to 10 in is typical — to add to the drop for turnings at top and bottom.
- Read the results live: how many fabric widths to cut, the cut length per width, and the total fabric to buy, including a +10% margin for shrinkage, pattern matching and cutting mistakes.
All calculations run in your browser, so nothing is uploaded and you can change any number as many times as you like. If you are working in inches and buying by the yard, the total comes out in inches with a rough yard figure shown alongside.
Worked Example: Calculating Yardage in Inches
To see how the numbers fit together, take a window with an 84 in (7 ft) track and a 72 in (6 ft) finished drop. The fabric is a standard 54 in wide cotton off a US roll, and you want a 2× gathered pencil pleat heading. Your hem and heading allowance is 9 in (about 4 in top turning plus 5 in bottom double hem).
Step 1 — number of widths. 84 in × 2 = 168 in of flat fabric needed. Divide by the 54 in fabric width: 168 ÷ 54 = 3.11 widths. Rounding up gives 4 widths.
Step 2 — cut length per width. 72 in drop + 9 in allowance = 81 in per cut length.
Step 3 — total yardage. 4 widths × 81 in = 324 in. Divide by 36 to get yards: 324 ÷ 36 = 9 yards of fabric exactly. With the +10% margin added, that is 9 × 1.1 = 9.9 yards, rounded up to 10 yards.
For a pair of curtains on this track, split the 4 widths into 2 widths per side. If the rounded total had been an odd number like 5, you would put 3 on one side and 2 on the other so both sides gather evenly when closed.
Common Fabric Widths Off the Roll
The widths you divide by come straight off the bolt, and they vary by fabric type and country of origin. The table below shows the most common widths in inches and the centimetre equivalents used in the calculator.
| Fabric type | Width in inches | Width in cm |
|---|---|---|
| Standard US decor | 54 in | 137 cm |
| Wide US quilting cotton | 60 in | 152 cm |
| Extra-wide sheeting | 108 in | 274 cm |
| UK / EU curtain lining | 54 in | 137 cm |
| UK / EU printed cotton | 48 in | 122 cm |
The wider the fabric, the fewer widths you need for the same track. A 108 in sheeting needs roughly half as many widths as a 54 in decor fabric for the same window, which often offsets the higher per-yard price of wide sheeting, especially on larger tracks.
Patterns, Pairs and the +10% Safety Margin
The basic formula assumes plain fabric, but most curtains are not plain. If your fabric has a pattern repeat — a stripe, a floral, a check — each cut length has to be rounded up to a whole repeat so the design lines up across widths. On a small repeat (say 10 cm) this adds little; on a large motif (50 cm or more) it can add a full repeat per width and inflate the total yardage considerably. For patterned fabric you should plan for more than the calculator's default 10% margin, especially on tall drops.
For a pair of curtains, the calculator returns a single total that covers the whole track. Split that total between the two sides, adding one extra width to one side if the rounded width count is odd so both panels gather evenly.
The +10% margin is the calculator's built-in safety net. It covers the usual losses: pattern matching at the seams, shrinkage after the first wash, and the small mistakes that always seem to happen on a long straight cut. For heavier patterned fabric, bump that buffer up to 15 to 20%. Always measure your window twice before ordering.
Measuring Tips Before You Order
The yardage is only as good as the measurements it is built on, so spend a moment on each one.
- Measure the track or pole width end to end, including any overlap at the centre if you want the curtains to meet cleanly when closed. Add 5 to 10 cm (2 to 4 in) of overlap to the total before entering it.
- Decide where you want the hem to fall — sill, apron, floor or puddle — and measure from the underside of the ring or hook, not from the top of the pole.
- Check the roll width on the bolt end or product page before you start, not after you have picked a fullness. A 48 in UK cotton and a 54 in US decor give very different numbers for the same window.
- For patterned fabric, find the vertical repeat on the selvedge and round each cut length up to the nearest whole repeat.
Once you have these numbers, enter them into the calculator and you will have a yardage you can order with confidence. For patterned fabric where the repeat is large or the design is directional, the dedicated guide on calculating curtain fabric with a pattern repeat walks through the extra steps in more detail.