Mooring Line Weight Chart: Weight Per Foot and Meter by Rope Diameter
You’re standing at the chandlery counter with two coils of rope, and the only difference you can see is the number stamped on the label—but one weighs almost twice as much as the other, and that matters more than you think.
TL;DR: Mooring line weight depends on three things: diameter, material, and construction. Nylon is heavier than polypropylene at the same diameter, polyester is heavier still, and a 24mm nylon line can weigh roughly 78 kg per 220 meters while a 12mm line of the same material weighs around 19.6 kg for the same length . Weight affects handling, winch capacity, and how much line you can carry—so knowing the numbers before you buy saves you from a line that’s too heavy to haul or too light for the job.
Key Takeaways
- Weight scales with diameter squared—doubling diameter roughly quadruples weight per foot.
- Nylon is heavier than polypropylene at the same diameter, but stronger and more stretchy .
- A 12mm nylon line weighs about 19.6 kg per 220 meters; a 24mm jumps to 78 kg for the same length .
- Polyester mooring lines are denser and heavier than nylon at comparable diameters .
- Safety reminder: Heavier isn’t always better. Oversized line strains winches, cleats, and your crew’s back.
The Weight Chart: Nylon and Polypropylene by Diameter
Here’s the real data from manufacturer tables. These numbers are for 3-strand, 4-strand, and 6-strand construction, measured in kilograms per 220 meters—a standard bulk length in the marine rope trade .
| Diameter (mm) | Diameter (inch, approx.) | Polypropylene Weight (kg/220m) | Nylon (Polyamide) Weight (kg/220m) | Nylon Weight (kg/100m) |
|---|---|---|---|---|
| 6 | 1/4 | 3.74 | 4.95 | ~2.25 |
| 8 | 5/16 | 6.60 | 8.80 | ~4.0 |
| 10 | 13/32 | 9.90 | 13.6 | ~6.2 |
| 12 | 15/32 | 14.30 | 19.60 | ~8.9 |
| 14 | 9/16 | 20.00 | 27.00 | ~12.3 |
| 16 | 5/8 | 25.30 | 35.00 | ~15.9 |
| 18 | 23/32 | 32.50 | 44.00 | ~20.0 |
| 20 | 13/16 | 40.00 | 54.00 | ~24.5 |
| 22 | 7/8 | 48.40 | 66.00 | ~30.0 |
| 24 | 15/16 | 57.00 | 78.00 | ~35.5 |
| 26 | 1-1/32 | 67.00 | 92.00 | ~41.8 |
| 28 | 1-1/8 | 78.00 | — | — |
Source: TradeChina manufacturer parameter table for 3/4/8/12 strand marine rope . Nylon kg/100m calculated by dividing the 220m figure by 2.2.
Quick conversion: To estimate pounds per foot from kg/100m, multiply by 0.0672. So a 16mm nylon line at ~15.9 kg/100m weighs roughly 1.07 lbs per foot. A 12mm nylon line at ~8.9 kg/100m weighs about 0.60 lbs per foot.
Here’s the pattern that matters: nylon is consistently 30–50% heavier than polypropylene at the same diameter. That’s the price you pay for strength and stretch.
Polyester: The Heavier, Denser Option
Polyester mooring lines aren’t always listed in the same tables, but manufacturer data shows they run heavier than nylon at comparable diameters.
Plastimo’s Blackgear polyester mooring line gives a clear picture :
| Diameter | Break Load | Weight per 100m |
|---|---|---|
| 8 mm | 1,450 kg | 4.9 kg |
| 10 mm | 2,150 kg | 7.7 kg |
| 12 mm | 2,550 kg | 10 kg |
| 14 mm | 3,330 kg | 13 kg |
| 16 mm | 4,550 kg | 17.5 kg |
| 18 mm | 5,680 kg | 21 kg |
| 20 mm | 6,600 kg | 27.5 kg |
Compare that to nylon at 12mm (around 8.9 kg/100m from the table above) and polyester at 12mm comes in at 10 kg/100m—slightly heavier. At 16mm, nylon is roughly 15.9 kg/100m while polyester is 17.5 kg/100m .
The difference isn’t dramatic, but it adds up over a full set of dock lines. Polyester’s higher density (specific gravity around 1.38 vs nylon’s 1.14) means it sinks faster and feels denser in hand .
If you’re counting ounces for a weight-sensitive application—like a racing boat or a tender—polypropylene is the lightest option. If you need durability and don’t mind the heft, polyester earns its weight.
Why Weight Matters More Than You Think
Line weight isn’t just a shipping cost. It changes how you use the line.
Handling. A 24mm nylon line at 78 kg per 220 meters is heavy. Hauling it by hand from a cleat to a winch gets old fast. Smaller crews and solo boaters feel this on every mooring. Lighter polypropylene is easier to throw, coil, and manage—but it’s weaker and degrades faster in UV.
Winch capacity. Every winch has a maximum line diameter and a drum capacity measured in meters of a specific line size. Going up a diameter step means you fit less line on the drum. A heavier, thicker line might not even fit the winch you have.
Stretch and surge. Heavier line carries more momentum when it moves. A heavy nylon line that’s too thick for the boat won’t stretch as designed under normal loads—it acts more like a cable and transfers shock to hardware instead of absorbing it.
Safety reminder: Don’t size up “just to be safe.” A line that’s too heavy for your cleats, winches, and crew is a different kind of hazard.
“The right line weight is the one that matches your boat’s displacement and your crew’s ability—not the one that looks most impressive on the coil.”
FAQ
How much does a 12mm mooring line weigh?
A 12mm nylon line weighs about 19.6 kg per 220 meters, or roughly 8.9 kg per 100 meters . That’s about 0.60 lbs per foot.
Is polypropylene lighter than nylon?
Yes. At 12mm, polypropylene weighs 14.3 kg per 220m while nylon weighs 19.6 kg per 220m . Polypropylene is lighter but weaker and less UV-resistant.
How do I convert kg/220m to pounds per foot?
Divide the kg/220m figure by 220 to get kg per meter, then multiply by 0.672 to get pounds per foot. Or just multiply the kg/220m number by 0.00305.
Does line weight affect breaking strength?
Weight is a rough proxy for material density and diameter, but not a direct measure of strength. Two lines of the same weight can have different breaking strengths depending on material and construction. Always check the manufacturer’s break load rating, not just the weight.
What’s the lightest mooring line material?
Polypropylene floats and is the lightest common option, with a specific gravity around 0.91 . But it sacrifices strength and UV resistance compared to nylon or polyester.
Why does polyester weigh more than nylon?
Polyester has a higher specific gravity (around 1.38) than nylon (around 1.14), so the same volume of fiber weighs more . It also tends to be denser in construction for mooring applications.
References
- TradeChina — 3/4/8/12 Strand Marine Mooring Polyamide Nylon Rope parameter table (weight and MBL by diameter for PP, PE, nylon, polyester). https://www.tradechina.com/3-4-8-12-Strand-Marine-Mooring-Fishing-Polyamide_10264029.html
- Plastimo — Blackgear polyester mooring line weight per metre and break load. https://www.plastimo-pro.com/en/448510-blackgear-polyester-mooring-line
- ShipServ / NIKA-FLEX — Mooring line weight table (kg/100m and kg/220m) and specific gravity data. https://www.shipserv.com/ShipServ/pages/supplierDetailId-651c41d900f6ff84c1d1cfa8/SupplierAdditionalDocuments/6ab0dc56123b565c41975077.pdf
What size and material are your dock lines—and have you ever been surprised by how heavy a new coil felt? Drop a comment below with your setup.
