Rope and twine are described by several overlapping units, and a request that only states “10 mm rope” is rarely enough to compare two suppliers. This guide explains the four units you will see most often, what each one tells you, and which one to use for which decision.
Diameter (mm)
Nominal diameter is the easiest unit to read and the most common error in cordage comparison. It is measured across the rope under a defined tension and is influenced by the yarn form, the lay and how soft the rope is. Two ropes labelled “10 mm” can be visibly different in real life, especially between a stiff PP 3-strand and a soft polyester double-braid.
Use diameter when:
- You are matching an existing rope, fixing or hardware
- You are speaking a common language with your customer or installer
- You are comparing products of the same material and construction
Do not use diameter alone when:
- You have a load requirement
- You are comparing different materials or constructions
- You are buying twine specified by runlength rather than diameter
Runlength (m/kg)
Runlength — meters per kilogram — is the standard for split-film twine, baler twine, PP/PE filament twine and most fishing twine. It is the actual measure that prices the tying point: a heavier bale needs a lower m/kg (heavier twine); a fine packing knot needs a higher m/kg (finer twine).
Typical ranges:
- Packing twine: 200–600 m/kg
- Baler twine: 80–200 m/kg depending on crop and bale weight
- Fishing twine: 100–1,000+ m/kg depending on denier × ply
Denier (D) and ply
Denier is the weight in grams of 9,000 meters of a single yarn. A twine specified as 210D/12 means twelve 210-denier yarns twisted together. The first number fixes the yarn; the second number fixes the size of the twine. This is the standard specification in fishing net twine.
Tex
Tex is the same idea as denier but in metric units — grams per 1,000 m of yarn. 1 denier = 1/9 tex. You will see tex mostly on European and industrial spec sheets.
What to put in the RFQ
For a 3-strand or braided rope, give: material, construction, diameter, color, length per unit, packaging and quantity.
For a twine, give: material, yarn form (split film / monofilament / multifilament), runlength (m/kg) or denier × ply, color, packaging and quantity.
For a netting, give: mesh size, cord diameter or runlength, finished panel dimensions, border treatment and quantity.
The more of these you include, the fewer clarifying questions you receive, and the more directly comparable the quotations will be.