Reference Charts
Some questions do not need a calculator. What drops do ready-made curtains come in, what does a quarter-inch seam allowance measure in millimetres, how wide is quilting cotton really — these are lookups, and a table answers them faster than a form. The charts here hold the same figures the calculators use, rendered from the same records, so a number cannot be right on one page and wrong on another.
Charts
Standard curtain sizes
Ready-made drops and widths, in both systems — and what each width really gathers to.
Fabric width chart
Standard roll widths in both systems, and the gap between the label and the cloth.
Seam allowance chart
Every common allowance in millimetres and inches, and which projects use which.
Fabric weight chart
Weight bands in g/m² and oz/yd², and what each band is actually used for.
Curtain heading types
Five headings compared on fullness, allowance and what they cost in cloth.
Why these are generated, not typed
Every table on this site is rendered from the record the calculators read. The ready-made curtain sizes come from one list, the roll widths from another, the seam allowances from a third — and the pages that explain them, the glossary entries that define them and the calculators that use them all draw on the same source.
That is not a tidiness preference. Before it was arranged this way the same figure could be explained in a field hint, an FAQ answer and a paragraph of page copy, three times, with nothing keeping them in step. A default that changed in the code left three stale sentences behind it. Generating the tables makes that failure impossible rather than merely unlikely.
What a chart will not tell you
A chart gives the convention. It cannot account for your window, your fabric or your shop. A ready-made curtain size tells you nothing about the fullness it will give until you divide it by your own track width; a roll width printed on a bolt end usually includes the selvedge, which is not usable cloth.
Where the answer depends on your measurements rather than on a convention, use a calculator instead — each one shows every allowance it adds and the arithmetic it used, so you can check it rather than trust it. Where it depends on converting between systems, the conversions use the exact defined ratios.
The vocabulary
Every term used across these tables is defined once, in the glossary — drop, fullness, roll width, selvedge, nap, pattern repeat, seam allowance and the rest. Each entry carries the figures the calculators use and links back to the tools that use them. Where a chart and a calculator disagree about what a word means, the glossary is the page that settles it.
The formulas behind every figure, and the assumptions each one rests on, are set out on the methodology page. Nothing here is rounded to the nearest anything: conversions are exact, and where cloth has to be bought it is always rounded up.