SAG Calculator
Subtract the square root of from to determine the sag.
The SAG Calculator computes the sagitta (SAG), a critical measurement in various fields such as construction, optics, and engineering. SAG quantifies the depth of a curve or arc over a specified diameter.
Formula
SAG = R − SQRT(R² − (D/2)²)
| Variable | Definition | 
|---|---|
| SAG | Sagitta (depth of the arc) | 
| R | Radius of the arc or circle | 
| D | Diameter of the chord (span length) | 
Solved Calculations
Example 1
A cable has a radius of 100 feet and a span of 20 feet.
| Variable | Value | 
|---|---|
| Radius (R) | 100 feet | 
| Diameter (D) | 20 feet | 
| Sagitta (SAG) | 0.5 feet | 
Example 2
A shelf with a 50-inch radius and a span of 30 inches.
| Variable | Value | 
|---|---|
| Radius (R) | 50 inches | 
| Diameter (D) | 30 inches | 
| Sagitta (SAG) | 2.25 inches |