Cable Reel Capacity Calculator – Free Online Tool

Ever ordered a cable reel and wondered exactly how much wire is actually on it — or how much reel you'll need for a bulk length of cable? Our free Cable Reel Capacity Calculator answers that in seconds, using your reel's flange diameter, barrel diameter, traverse length, and cable diameter.

Why use a reel capacity calculator?

Whether you're a hobbyist stocking up on wire for an electronics project, or a business planning how many reels you need for a bulk cable order, getting this number wrong is costly — order too little reel capacity and you waste material on odd cuts; underestimate cable diameter and you overpay for extra reels you didn't need.

This tool takes the guesswork out of it by calculating:

• Maximum Reel Capacity — the theoretical maximum length of cable that fits on the reel
• Recommended Cable Length — a safer estimate (about 80% of maximum) accounting for real-world winding looseness, tension variation, and material behavior

What you'll need to enter

• Flange Diameter (A) — the total outer diameter of the reel
• Barrel Diameter (B) — the diameter of the reel's core, where winding starts
• Traverse Length (C) — the inner width of the reel, between the two flanges
• Cable Diameter (D) — the thickness of the cable you're winding
• Edge Clearance (E) — optional free-board space near the flange edges, if your reel design requires it

Switch between Metric and Imperial units depending on what your reel and cable specs are in.

A quick example

Note: results are theoretical estimates. Actual capacity can vary slightly depending on winding tension, cable lay, and material — always verify against your actual reel and cable specs before placing large orders.