How to Measure Curtains and Calculate Fabric Yardage
Quick answer: how do you calculate curtain fabric?
Measure the finished width of the curtain pole or track, multiply it by the fullness required for the chosen heading, and divide that result by the usable width of the fabric. Round up to a whole number of fabric widths—and, for a matching pair, normally to an even number. Then multiply the number of widths by the cut length for each drop.
The cut length is the finished curtain drop plus the top heading allowance, bottom hem and any allowance for pattern matching or expected shrinkage. Convert the final total into yards or metres and add a sensible cutting contingency before ordering.
What you need before measuring
- a metal tape measure long enough for the window;
- the installed curtain pole or track, where possible;
- the chosen heading style or curtain-making pattern;
- the fabric’s full and usable width;
- vertical and horizontal pattern-repeat information;
- the proposed top and bottom allowances; and
- confirmation of whether the fabric is prewashed or requires shrinkage allowance.
Use one measurement system from beginning to end. Mixing centimetres and inches is an easy way to create an expensive error.
Measure the pole or track—not just the window
For most curtain calculations, measure the working width of the installed pole or track rather than the glass or recess. Exclude decorative finials from a pole measurement. If the hardware is not installed, decide how far it will extend beyond each side of the window before calculating fabric.
Measure in at least two places and record the result clearly. Old walls and window openings may not be perfectly square. If a track bends around a bay, measure along the route the curtain actually travels rather than taking a straight line across the opening.
Measure the finished curtain drop
The starting point depends on the heading and hardware:
- Track with hooks: measure from the relevant hook or glider position specified by the heading system.
- Pole with rings: measure from the lower edge of the ring or the hook position, depending on the chosen finish.
- Eyelet curtains: follow the pattern or eyelet instructions and include the fabric that will sit above the pole.
- Rod pocket: measure from the intended top of the pocket and include the pocket and any heading above it.
Measure down to the chosen finish: sill length, below-sill, floor-skimming or a deliberate puddle. For floor-length curtains, check both sides and the centre because floors and hardware can be uneven.
Choose the curtain fullness
Fullness is the ratio between the flat curtain width and the pole or track width. A ratio of 2 means the flat fabric is twice the width of the space it covers.
| Fullness | Typical visual effect | Important note |
|---|---|---|
| 1.5× | Relaxed, relatively flat folds | Can suit informal linen curtains, but may look sparse with some headings. |
| 2× | Balanced everyday fullness | A useful planning figure for many styles. |
| 2.5× | Deeper, more generous folds | Often needs more fabric and careful stacking space. |
These are planning ranges, not rules. Pencil pleat tape, pinch pleats, wave systems, eyelets and gathered headings can require different ratios. Follow the hardware or heading manufacturer’s recommendation before buying fabric.
Calculate the total finished width
Use this formula:
Pole or track width × fullness ratio = total flat curtain width.
For example, a 96-inch track at 2× fullness needs 192 inches of flat curtain width across the complete treatment. If you are making a pair, each finished curtain accounts for half of that total.
Calculate how many fabric widths you need
Check the usable fabric width after excluding selvedges or any edge that cannot form part of the finished panel.
Total flat curtain width ÷ usable fabric width = number of fabric widths.
Always round up. For a matching pair of curtains, an odd result is normally rounded up again to an even number so each curtain contains the same number of widths. This may produce slightly more fullness than the original ratio, which is usually preferable to an under-filled pair.
Calculate the cut length for each width
Start with the finished drop, then add the allowances required by the actual heading and construction:
Finished drop + heading allowance + bottom hem + other construction allowances = basic cut length.
Do not rely on one universal hem figure. A hand-finished interlined curtain, a simple unlined panel and an eyelet curtain can require different amounts. Use the curtain pattern or workroom specification.
Allow for a vertical pattern repeat
Plain linen is straightforward because each width can normally use the same basic cut length. With a patterned fabric, adjacent widths must begin at matching points in the design.
A common calculation is:
Basic cut length ÷ vertical repeat, rounded up to the next whole repeat = pattern-adjusted cut length.
If the basic cut length is 104 inches and the vertical repeat is 27 inches, four repeats are needed, producing a 108-inch cut length. Half-drop designs and fabrics with a directional motif may need a different layout, so confirm the repeat type before cutting.
Worked curtain-yardage example
Imagine a pair of plain linen curtains with these measurements:
- track width: 96 inches;
- planned fullness: 2×;
- usable fabric width: 54 inches;
- finished drop: 90 inches; and
- combined heading and hem allowances: 14 inches.
- Total flat width: 96 × 2 = 192 inches.
- Fabric widths: 192 ÷ 54 = 3.56, rounded up to 4 widths.
- Each curtain receives 2 fabric widths.
- Basic cut length: 90 + 14 = 104 inches.
- Total fabric length: 4 × 104 = 416 inches.
- Yardage: 416 ÷ 36 = 11.56 yards.
You would round up to the retailer’s selling increment and add an appropriate contingency for straightening cuts and construction. If the same fabric had a 27-inch vertical repeat, each cut would become 108 inches, giving 432 inches or 12 yards before contingency.
Convert metres and yards correctly
One yard equals 36 inches or 0.9144 metres. One metre equals approximately 1.094 yards. Keep the calculation in the unit used for the original measurements, then convert once at the end.
Our guide to how big a yard of fabric is explains linear yardage and fabric width in more detail.
Allow for hems, shrinkage and straightening
Fabric can arrive with a cut edge that needs squaring before accurate panels are cut. Allow for this rather than assuming every centimetre or inch from the bolt is usable.
If the curtain fabric or finished curtains will be washed, follow the supplier’s preparation guidance. Do not automatically prewash a fabric that is specified for professional cleaning, treated, backed or otherwise unsuitable for home washing. Where shrinkage allowance is required, use the supplier’s documented figure rather than guessing.
See how to prepare linen before sewing for project-specific prewashing considerations.
Do lining and interlining change the calculation?
They do not usually change the number of face-fabric widths, but they require their own yardage calculations and construction allowances. Lining width may differ from the face fabric, and interlining may be cut or joined differently.
Calculate face fabric, lining, interlining, heading tape and trims separately. If the project uses blackout lining, confirm its orientation and care compatibility with the linen face fabric.
Consider railroading only when the fabric allows it
Railroading means turning the fabric so its width runs along the curtain drop or across the finished treatment. Extra-wide plain fabric can sometimes reduce seams, but not every weave, pattern or finish is suitable for use in the alternate direction.
Only railroad fabric when the supplier confirms that the construction and design permit it. Directional motifs, nap and some woven structures must remain in their intended orientation.
Order a sample before ordering yardage
A sample lets you check colour, opacity, drape and scale in the room. Hold it against the window in daylight and artificial light, and assess whether lining is required. Browse linen fabric samples before committing to the full quantity.
For curtain-suitable cloth, see the Linen Curtains fabric collection. Confirm fabric width, repeat, care and stock availability for the exact option selected.
Common curtain-measuring mistakes
- measuring the glass instead of the installed pole or track;
- including decorative finials in the working width;
- forgetting that a curtain pair needs equal numbers of widths;
- using the full fabric width when selvedges must be excluded;
- ignoring the heading system’s required fullness;
- forgetting the vertical repeat or half-drop pattern;
- assuming removable curtains can automatically be machine washed; and
- ordering the exact mathematical result without a cutting contingency.
Final measurement checklist
- Hardware installed or final dimensions confirmed.
- Pole or track width recorded without finials.
- Drop measured from the correct heading point.
- Fullness confirmed for the heading system.
- Usable fabric width and pattern repeat checked.
- Top, bottom and side allowances specified.
- Number of widths rounded appropriately for a pair.
- Face fabric, lining and interlining calculated separately.
- Final total converted once and rounded to the selling increment.
Frequently asked questions
How much fullness should linen curtains have?
Many linen curtains are planned between 1.5× and 2.5× fullness, but the correct ratio depends on the heading system, fabric weight and desired appearance. Follow the hardware or heading recommendation.
Do I measure the window or the curtain pole?
For most made curtains, measure the working width of the installed pole or track, excluding decorative finials. A recess-mounted treatment may use different measurements.
How do I calculate fabric for a pair of curtains?
Calculate the total flat width for both curtains, divide it by the usable fabric width and round up. If the result is odd, normally round up to an even number so both curtains have matching widths.
How much extra fabric should I buy?
Allow for pattern matching, squaring the cut edge, construction and the retailer’s selling increment. The appropriate contingency depends on the fabric and project, so confirm it with the curtain maker before ordering.
