SAG (Cable Sag) Calculator

Find the sag of a suspended cable or conductor.

Weight per length (lb/ft)

Span

Tension

Sag 0.0001

Formula: sag = w·L² ÷ (8·T)

Step-by-step with your numbers:

1. Values used:

2. Weight per length = 0.5 lb/ft

3. Span = 1

4. Tension = 500

6. Sag = 0.0001

Did we solve your problem today?

Find how much a cable or wire sags between two supports.

The math behind it

sag ≈ weight per length × span² ÷ (8 × tension), for a shallow, evenly-loaded cable.

0.5 lb/ft over 100 ft at 500 lb → 1.25 ft sag.

More tension?

Reduces sag, but increases stress on supports.