Cable length Calculator: measuring notes and method
Trace the actual cable route
Include rises, drops and routes around obstructions rather than the straight distance between endpoints. Record different cable types separately and add termination lengths explicitly.
Check reel and run constraints
Runs that must remain continuous need a cable schedule. Enough total cable on several short reels may still be insufficient for one long run.
Formula
Required length = length per run × runs × (1 + waste ÷ 100). Stock count = required length ÷ stock length, rounded up.
Worked examples in metric and imperial units
Illustrative values match Reset example and stay fixed when you edit the calculator. Both columns describe the same calculation; converted inputs are rounded.
Metric worked example
- Required length per run
- 6 m
- Quantity
- 1
- Stock length
- 3 m
- Waste allowance
- 10 %
Stock lengths / reels to buy: 3
Imperial worked example
- Required length per run
- 19.685 ft
- Quantity
- 1
- Stock length
- 9.8425 ft
- Waste allowance
- 10 %
Stock lengths / reels to buy: 3
Follow the calculation
Lengths in this working are in metres.
- Net required length = 6 × 1 = 6 m.
- Stock count = 6 × 1.1 ÷ 3, rounded up. This assumes usable offcuts.
Reviewed 19 October 2026. How calculations are checked · Report a correction