Construction

SAG (Cable Sag) Calculator

Find the sag of a suspended cable or conductor.

Weight per length (lb/ft)

Span

Tension

Calculated Output

Sag 0.0001

Formula: sag = w·L² ÷ (8·T)

Step-by-Step Breakdown

1. Values used:

2. Weight per length = 0.5 lb/ft

3. Span = 1

4. Tension = 500

6. Sag = 0.0001

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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.