Fabric and curtain terms
The terms the calculators on this site use, defined once and linked from wherever they appear. Where a figure comes from the calculators' own data — heading allowances, weight bands, nominal roll widths — it is rendered from that data rather than retyped, so a definition here cannot drift from the tool that uses it.
Buying cloth
What the label on the end of the roll is telling you, and what it is quietly not.
- Roll width also Bolt width, Fabric width
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How far the cloth reaches from one side edge to the other — the length of the tube it is wound round. It is fixed by the loom and never changes, however much you buy; the length is the part that unwinds. Because it is fixed, it decides how many pieces sit side by side, and that decides the length you have to buy.
Six 45 cm squares on a 140 cm roll. Three fit across, so six take two rows — and the hatched strip down the side is width you buy and cannot use. Used by fabric yardage calculator, cushion fabric calculator, fabric width converter.
- Nominal width
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The width a cloth is sold as, which is a trade name rather than a measurement. The industry treats "54 inch" and "140 cm" as one thing; 54 inches is 137.2 cm, nearly 3 cm narrower. On a wide piece that gap decides whether it fits.
What each trade name actually measures. Sold as Actually Usually 36 in / 90 cm 91.4 cm Quilting cottons, older dress fabrics 44 in / 112 cm 111.8 cm Standard quilting cotton 45 in / 115 cm 114.3 cm Dressmaking cottons, commercial patterns 54 in / 137 cm 137.2 cm Upholstery, curtain lining 55 in / 140 cm 139.7 cm Curtain and furnishing fabrics 60 in / 150 cm 152.4 cm Knits, wide dress fabrics 108 in / 274 cm 274.3 cm Wide-back quilting fabric Three metres of 115 cm cloth against the same area on a 150 cm roll. Equal areas only: how the pieces actually nest is not modelled, and the converter says so. Used by fabric width converter, fabric width chart.
- Selvedge also Selvage
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The finished edge running down each side of the cloth, woven so it cannot fray. It is often stiffer than the rest, sometimes printed with the maker’s name, and usually cut away — so a roll sold as 140 cm may give less than 140 cm of usable width.
Used by fabric yardage calculator, upholstery fabric calculator, fabric width converter, cushion fabric calculator.
- Bolt
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The unit a mill ships cloth in: a full length wound on a board or tube, typically 30 to 100 metres. A shop cuts your piece from the bolt, so the bolt end is where the width, the composition and the pattern repeat are printed.
Used by fabric width converter.
- Cut increment
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The smallest step a counter will cut to. Ask for 2.34 m and you will be sold 2.4 m, so every total on this site is rounded up to the increment you choose rather than to the nearest one.
The increments these calculators will round up to. Cuts to Step Where Nearest 10 cm 0.1 m Most UK and European shops cut roll goods to the nearest 10 cm. Nearest half metre 0.5 m Common for upholstery weights and wholesale bolts. Whole metres 1 m Some mills and online sellers cut only in whole metres. Nearest ⅛ yard 0.125 yd The standard cut at a US quilting counter. Nearest ¼ yard 0.25 yd Common for general dress and home-furnishing fabrics in the US. Exact requirement — No rounding — useful when you are cutting from fabric you already own. Used by yards to metres, metres to yards.
Curtains
The four measurements a workroom asks for, and the one choice that changes all of them.
- Heading
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The top of the curtain, and the way it is gathered onto whatever holds it up. The style chosen sets both how much cloth is turned down at the top and how much fullness the curtain needs before it will pleat at all.
The five styles, and what each asks for. Style What it is Top Fullness Pencil pleat Drawn up by a corded tape into narrow, even folds. The tape does the gathering rather than the pole, so it wants more cloth than any other common heading. 15 cm 2× min Pinch pleat Folds sewn into fixed groups of two or three and pinched at the base, so the pleats stay where they were put. Formal, and cheaper in cloth than a pencil pleat. 20 cm 2× min Eyelet Metal rings punched through a stiffened band, threaded straight onto a pole. The pole forms the folds instead of a tape, which is why it needs less fullness — but the band is deep, so it takes the most at the top. 25 cm 1.8× min Tab top Loops of the same cloth passed over a pole. The flattest heading here: the fabric hangs almost straight, so it needs the least of everything. 12 cm 1.5× min Wave A corded tape at fixed spacing on a track made for it, giving one continuous even S from end to end. It only works on that track — an ordinary one will not hold the spacing. 15 cm 2× min The five styles, drawn. Shapes only — the calculation models a heading as an allowance and a minimum fullness, and no pleat spacing at all, so nothing here carries a measurement. Used by curtain fabric calculator, curtain fullness calculator, curtain heading tape calculator, curtain heading types.
- Fullness
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How much wider the flat cloth is than the space it has to cover, as a multiple. At 2× fullness a 100 cm track takes 200 cm of flat fabric, and the extra 100 cm is what becomes the folds.
One curtain of a pair on a 200 cm track at 2.5x fullness. The slivers at the two outer edges are side hems; the band in the middle is the two seam allowances a join costs. Used by curtain fullness calculator, curtain fabric calculator, curtain lining calculator, standard curtain sizes.
- Drop
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The finished length of a curtain, measured from where it hangs to where it should stop — from the hook, ring or eyelet position, not from the pole itself. The pole sits above that point, so measuring from it makes every curtain too long.
Used by curtain fabric calculator, roman blind fabric calculator, pattern repeat calculator, standard curtain sizes.
- Return and overlap
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The return is the bit that wraps back to the wall at each end of a track, so light does not come round the side. The overlap is where a pair crosses in the middle. Both are gathered like the rest, so both are added before fullness is applied.
Used by curtain fullness calculator.
Down the roll
Everything that decides which way a piece has to lie, and what that costs.
- Pattern repeat also Vertical repeat, Straight repeat
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The distance up the roll from one point in the design to the identical point on the next — whatever the size of the motif itself. Every piece that has to match its neighbour must be cut to a whole number of repeats, which is why matched cloth costs more than its length suggests.
A 220 cm drop with 35 cm of allowances, on a 64 cm repeat. The cut has to end on a repeat mark, so it runs past what the piece needs and the tail is trimmed off. Used by pattern repeat calculator, curtain fabric calculator, roman blind fabric calculator.
- Half-drop repeat
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A repeat where the design steps down by half its height between adjacent widths instead of lining up straight across. It costs an extra half repeat on every width after the first. The calculators here assume a straight repeat and say so.
Used by pattern repeat calculator.
- Grain, and the bias
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The grain is the direction the threads run: lengthways down the roll, crossways from selvedge to selvedge. The bias is the 45° diagonal between them, which is the only direction woven cloth stretches — so strips cut on the bias go round a curve, and cost about 41% more cloth to do it.
- Nap
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A pile or a print that only works one way up — velvet, corduroy, a one-way floral. Every piece must be cut running the same direction, so pieces cannot be turned to pack them in more tightly, and the job takes more cloth.
Used by fabric yardage calculator, fabric width converter, tablecloth fabric calculator.
- Railroading
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Running the cloth sideways, so the roll width becomes the height of the panel rather than its width. On something wide it removes the seams entirely and usually saves fabric — but only on cloth sold as railroadable, because on most upholstery weights the strong direction runs down the roll.
Used by upholstery fabric calculator.
Making up
The difference between the size you cut and the size you end up with.
- Seam allowance
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The strip between the cut edge and the line you sew along, which ends up inside the work. It is added to every edge that will be sewn, so a piece grows by twice the allowance in each direction it is seamed.
What each allowance is for. Allowance Used for ¼ in Patchwork and quilting, where every seam is pieced. ⅜ in Overlocked knits and fine seams. 1 cm European patterns, bag making, home furnishing. ½ in General home sewing, US patterns for straight seams. 1.5 cm The metric dressmaking standard. ⅝ in The imperial dressmaking standard. Not the same as 1.5 cm. 2 cm Curtains, loose covers, anything that may be let out. A piece finishing 50 x 60 cm, sewn at 1.5 cm on all four edges. The corner is magnified because at true scale the allowance is a hairline — the factor is printed rather than the scale quietly exaggerated. - Side hem
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The turning down each outer edge of a finished curtain. It belongs to the two outer edges only — the joins between widths are seams, not hems — and charging one per width is the commonest way to over-order.
One curtain of a pair on a 200 cm track at 2.5x fullness. The slivers at the two outer edges are side hems; the band in the middle is the two seam allowances a join costs. Used by curtain fullness calculator, curtain fabric calculator.
- Cut length, and finished size
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The cut length is what you mark on the roll; the finished size is what you have after sewing. Everything between them — hems, turnings, seam allowances, and any rounding up to a whole pattern repeat — is cloth you buy and never see.
A 220 cm drop with 35 cm of allowances, on a 64 cm repeat. The cut has to end on a repeat mark, so it runs past what the piece needs and the tail is trimmed off. Used by seam allowance calculator, pattern repeat calculator, curtain fabric calculator.
Weight
Four units for one property, three of which need context to mean anything.
- GSM also Grams per square metre, g/m²
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What a square metre of the cloth weighs. It describes the fabric itself rather than the roll, which is what makes it the one weight figure that means the same thing whoever quotes it.
The bands, and what tends to sit in each. Band Range Typically Very light under 80 g/m² Chiffon, organza, voile, fine lining. Sheer; needs care to sew. Light 80–120 g/m² Lawn, batiste, shirting, quilting cotton, dress cotton. Medium 120–200 g/m² Poplin, twill, jersey, linen, most dressmaking and quilting. Heavy 200–300 g/m² Denim, drill, curtain fabric, light upholstery, bag fabric. Very heavy 300–400 g/m² Upholstery weight, heavy canvas, outdoor fabric, coating. Extra heavy over 400 g/m² Heavy upholstery, tarpaulin, rug and carpet backing. Where 150 g/m2 sits. The bands are drawn the same size as each other, not to scale, because their real ranges run from 80 to unbounded and an axis would make the common weights unreadable. Used by fabric gsm calculator, fabric weight chart.
- Running yard also Linear yard
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A yard of length off the roll, whatever the roll is wide. So a weight quoted per running yard describes the roll as much as the cloth: the same "12 oz" is a heavier fabric on a narrow roll than on a wide one.
Four units for one property. Unit Short What it tells you Grams per square metre g/m² The metric standard, and the only one that describes the cloth rather than the roll. Ounces per square yard oz/yd² The US standard for most woven fabric. Ounces per running yard oz/yd Used for denim and canvas. Depends on the roll width, so it says as much about the roll as the cloth. Momme mm The silk unit: the weight in pounds of 100 yards by 45 inches. Used by fabric gsm calculator.
- Momme
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The silk trade’s weight unit: what a piece 100 yards long and 45 inches wide weighs, in pounds. One momme is about 4.34 g/m². The conversion works on anything, but nobody will know what a 12-momme cotton is.
Used by fabric gsm calculator.