Cable Reel Capacity / Length on Reel
How many feet of a given cable fit on a reel (or how much is left on a partial reel).
Example
You enter
- Reel flange diameter (in) 30
- Drum / hub diameter (in) 12
- Inside width between flanges (in) 18
- Cable outside diameter (in) 1
- Winding fill factor 0.9
You get
- Cable that fits on the reel 802 ft
Checked against published worked examples from: Southwire Company.
Details, formula, and sources
Scopelength = fill x pi x (flange^2 - drum^2) x traverse / (48 x cable_OD^2), lengths in inches. A 30 in flange, 12 in drum, 18 in wide reel holds ~801 ft of 1 in cable; a fatter 1.5 in cable drops it to 356 ft, since the cable OD enters squared. The figure that tells the crew whether the pull is on one reel or two.
Formula or tablelength_ft = fill_factor x PI x (flange_dia_in^2 - drum_dia_in^2) x traverse_width_in / (48 x cable_od_in^2).
Source and editionReel-capacity identity by name (annular winding volume / cable cross-section, with a fill factor); first-principles geometry.
Free accessThe reel-capacity geometry is public first-principles; the reel dimensions come from the reel and the cable OD from the cable.
What governsEstimate. AHJ and licensed professional govern.
API field namesflange_dia_in, drum_dia_in, traverse_width_in, cable_od_in, fill_factor, length_ft
- Fill factor ~0.85-0.9 for imperfect winding; the winding pattern governswinding practice
- Cable OD the cable outside diameter; it enters squared, so a fatter cable cuts the reel sharplycable manufacturer