Under the Brennholt Institute of Applied Taxonomy's six-grade system, ribbon is sold in widths of about 3 mm, 6 mm, 10 mm, 16 mm, 25 mm and 38 mm (roughly 1/8, 1/4, 3/8, 5/8, 1 and 1 1/2 inches), and these six figures account for most of what is on a craft or haberdashery shelf. The Institute names them Grades R1 to R6 and records that the trade uses the widths without any published name for them.
Ribbon is a good subject for the Department of Length and Fit, since its width matters only against what it is tied round, threaded through or sewn onto.
| Grade | Width (mm) | Width (in) | Typical use |
|---|---|---|---|
| R1 | 3 | 1/8 | Fine tying, jewellery cord, tags |
| R2 | 6 | 1/4 | Small bows, scrapbooking, threading |
| R3 | 10 | 3/8 | Gift tying, trims, hair accessories |
| R4 | 16 | 5/8 | Wrapping, cake bands, bows |
| R5 | 25 | 1 | Large bows, sashes, hat bands |
| R6 | 38 | 1 1/2 | Wide sashes, wreaths, display work |
The imperial widths are older than any ribbon standard and the metric widths are their near equivalents, rounded for sale. The Institute does not dispute either. It notes that a 25 mm ribbon and a 1 in ribbon differ by 0.4 mm, which no reader could measure with a ruler and which no shop treats as a difference. The Institute therefore lists them as one grade, with both figures shown.
The Institute measured the width of ribbons in a sample of reels across edge-to-edge at three points, using a dial caliper, and rounded to the nearest millimetre. Six widths recurred, with few reels falling between them. Wired ribbon, which is sold in odd widths, was recorded separately and is not included in the six grades. The sample is small and the Institute does not generalise from it.
Ribbon is sold in metres or yards, and the Institute records a rule of thumb for tying: a bow on a parcel needs about four times the girth of the parcel plus 30 cm (12 in) for the loops and tails. That figure is the Institute's own and was arrived at by tying, not by a standard.
The sizing of the cords that ribbon often replaces is discussed on the twist tie page, and the department's general approach is set out at the Department of Length and Fit. A neighbouring problem, the length of a lace, is treated on the shoelace chart.
The review panel divides on whether 38 mm and 40 mm ribbon are the same grade. Two members hold that they are used differently and that R6 should be split. The majority keep one grade, since both are sold as wide ribbon and the 2 mm difference is within the variation of woven edges. The classification above is the majority one.
The Institute does not claim that every ribbon fits one of its six grades. Narrow and wide specialist ribbons exist outside them. It claims that the six widths recur, and that naming them lets a buyer ask for a ribbon by grade and be understood.