Cable Sag Calculator

Install Free from the Microsoft Store
Spiderweb with dew drops showing a natural example of catenary curves
Mtpaley, CC BY 3.0, via Wikimedia Commons

The information presented in this blog post is for educational purposes only. It should not be used for engineering design or relied upon as engineering advice.

Cables or wires suspended between supports exhibit a characteristic curved shape that is called a catenary curve. The sheet below calculates the sag of a cable given the cable length and horizontal separation between the supports. This calculation requires numerically solving a system of nonlinear equations. This example leverages the numerical system solving capability that was recently added to In addition to solving for the sag given the cable length and horizontal separation, the cable length can also be solved for given the desired sag. This can be done with only a slight modification to the sheet (the required changes are described in the sheet below).

This catenary sag calculator  may also be opened in a separate tab.

Cable Sag Calculator
by u/mgreminger in EngineeringPaperXYZ
Install Free from the Google Play Store