General reference only. Consult your wire rope distributor when specifying wire rope for your application.
Cable capacity
Drum cable capacity
Cable Capacity in Feet = b2 − a24 × c × R
- a
- drum core diameter, in.
- b
- flange diameter, in.
- c
- width between flanges, in.
- R
- rope factor for the rope size (table below)
Cable capacity, strength and weight
| Size | Construction | Minimum breaking strength (lbs) | Approx. weight (lbs/ft) | R (capacity factor) |
|---|---|---|---|---|
| 1/8" | 7×19 | 2,000 | 0.03 | 13.2 |
| 3/16" | 7×19 | 4,200 | 0.07 | 6.14 |
| 1/4" | 7×19 | 7,000 | 0.12 | 3.29 |
| 5/16" | 7×19 | 9,800 | 0.18 | 2.21 |
| 3/8" | 7×19 | 14,400 | 0.26 | 1.58 |
| 7/16" | 7×19 | 17,600 | 0.35 | 1.19 |
| 1/2" | 6×19 class | 26,600 | 0.46 | 0.925 |
| 9/16" | 6×19 class | 33,600 | 0.59 | 0.741 |
| 5/8" | 6×19 class | 41,200 | 0.72 | 0.607 |
| 3/4" | 6×19 class | 58,800 | 1.04 | 0.428 |
| 7/8" | 6×19 class | 79,600 | 1.42 | 0.308 |
| 1" | 6×19 class | 103,400 | 1.85 | 0.239 |
| 1-1/8" | 6×19 class | 130,000 | 2.34 | 0.191 |
| 1-1/4" | 6×19 class | 159,800 | 2.89 | 0.152 |
| 1-3/8" | 6×19 class | 192,000 | 3.50 | 0.127 |
| 1-1/2" | 6×19 class | 228,000 | 4.16 | 0.107 |
| 1-5/8" | 6×19 class | 264,000 | 4.88 | 0.088 |
| 1-3/4" | 6×19 class | 306,000 | 5.67 | 0.077 |
| 1-7/8" | 6×19 class | 348,000 | 6.50 | 0.067 |
| 2" | 6×19 class | 396,000 | 7.39 | 0.06 |
Cable capacity conversion factors
Know a drum’s capacity in one rope size and need it in another? Find the known size in the left column. To convert to a smaller rope (column), multiply by the factor. To convert from a column size back to a row size, divide.
| Known size | 1/8" | 3/16" | 1/4" | 5/16" | 3/8" | 7/16" | 1/2" | 9/16" | 5/8" | 3/4" | 7/8" | 1" | 1-1/8" | 1-1/4" | 1-3/8" | 1-1/2" | 1-5/8" | 1-3/4" | 1-7/8" |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2" | 220 | 102 | 54.8 | 36.8 | 26.3 | 19.8 | 15.4 | 12.4 | 10.1 | 7.13 | 5.13 | 3.98 | 3.18 | 2.53 | 2.12 | 1.78 | 1.47 | 1.28 | 1.12 |
| 1-7/8" | 197 | 91.6 | 49.1 | 33.0 | 23.6 | 17.8 | 13.8 | 11.1 | 9.06 | 6.39 | 4.60 | 3.57 | 2.85 | 2.27 | 1.90 | 1.60 | 1.31 | 1.15 | |
| 1-3/4" | 171 | 79.7 | 42.7 | 28.7 | 20.5 | 15.5 | 12.0 | 9.62 | 7.88 | 5.56 | 4.00 | 3.10 | 2.48 | 1.97 | 1.65 | 1.39 | 1.14 | ||
| 1-5/8" | 150 | 69.8 | 37.4 | 25.1 | 18.0 | 13.5 | 10.5 | 8.42 | 6.90 | 4.86 | 3.50 | 2.72 | 2.17 | 1.73 | 1.44 | 1.22 | |||
| 1-1/2" | 123 | 57.4 | 30.8 | 20.6 | 14.8 | 11.1 | 8.64 | 6.92 | 5.67 | 4.00 | 2.88 | 2.23 | 1.78 | 1.42 | 1.19 | ||||
| 1-3/8" | 104 | 48.4 | 25.9 | 17.4 | 12.4 | 9.37 | 7.28 | 5.84 | 4.78 | 3.37 | 2.42 | 1.88 | 1.50 | 1.20 | |||||
| 1-1/4" | 86.8 | 40.4 | 21.6 | 14.5 | 10.4 | 7.83 | 6.09 | 4.88 | 3.99 | 2.82 | 2.03 | 1.57 | 1.26 | ||||||
| 1-1/8" | 69.1 | 32.2 | 17.2 | 11.6 | 8.27 | 6.23 | 4.84 | 3.88 | 3.18 | 2.24 | 1.61 | 1.25 | |||||||
| 1" | 55.5 | 25.7 | 13.8 | 9.25 | 6.66 | 4.98 | 3.87 | 3.10 | 2.54 | 1.79 | 1.29 | ||||||||
| 7/8" | 42.9 | 19.9 | 10.7 | 7.18 | 5.13 | 3.86 | 3.00 | 2.41 | 1.97 | 1.39 | |||||||||
| 3/4" | 30.8 | 14.4 | 7.69 | 5.16 | 3.69 | 2.78 | 2.16 | 1.73 | 1.42 | ||||||||||
| 5/8" | 21.8 | 10.1 | 5.42 | 3.64 | 2.60 | 1.96 | 1.52 | 1.22 | |||||||||||
| 9/16" | 17.8 | 8.29 | 4.44 | 2.98 | 2.13 | 1.61 | 1.25 | ||||||||||||
| 1/2" | 14.3 | 6.64 | 3.56 | 2.39 | 1.71 | 1.29 | |||||||||||||
| 7/16" | 11.1 | 5.16 | 2.76 | 1.86 | 1.41 | ||||||||||||||
| 3/8" | 8.35 | 3.89 | 2.08 | 1.40 | |||||||||||||||
| 5/16" | 5.97 | 2.78 | 1.49 | ||||||||||||||||
| 1/4" | 4.01 | 1.87 | |||||||||||||||||
| 3/16" | 2.15 |
Example: a drum that holds 100 ft of 1/2" rope holds about 100 × 1.71 = 171 ft of 3/8" rope.
How the selector sizes rope
The Winch & Hoist Selector checks rope strength, D:d and freeboard against the standard you choose:
| Standard | Applies to | Rope design factor | Recommended min. D:d | Freeboard |
|---|---|---|---|---|
| ASME B30.16 | Hoists | 5:1 | 18:1 | 1 × rope diameter |
| ASME B30.7 | Winches | 3.5:1 | 15:1 | 1/2" |
| EN 14492-1 / general | Winches | 2:1 | 10:1 | 1.5 × rope diameter |
Design factor = minimum breaking strength ÷ line pull. D:d = drum core diameter ÷ rope diameter. Freeboard = clearance left between the top layer of rope and the flange edge.
Why hoists and winches use different rope: Winches Versus Hoists.