Short answer: subtract. Fiber cable is printed with sequential length marks along its jacket, so the mark at the outside end minus the mark at the inside end is the cable on the reel. FutureNet Telecom USA buys partial reels the same way as full ones once that number is known.
Find the length mark nearest the outside end of the cable, then the mark on the tail that comes out through the flange. Take the difference.
24,875 ft on the tail, 18,420 ft at the outside end: 24,875 − 18,420 = 6,455 ft on the reel.
The marks can count up or down depending on which end was wound first. Either way, the difference is the length.
An OTDR reading. It measures the length of the glass, not the jacket, and loose-tube cable carries extra fiber inside its tubes so the glass is never pulled tight. The Fiber Optic Association puts that at 1–2% for most cables, less for ribbon (Fiber Optic Association, OTDR FAQs). Divide the OTDR length by about 1.01 to 1.02 for the cable length.
Weight. The net weight of the cable divided by the weight per 1,000 ft on the manufacturer’s spec sheet gives a rough number. Reel weight and moisture make it rough.
Or send what you can see. Unknown footage is priced cautiously, and the offer says so plainly. Confirmed footage is priced on its full length.
Photos of the tags and your ZIP. Firm written offer within 24 hours. Freight is ours.
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