What does sag correction apply to in taped measurements?

Sag correction is applied to account for the effect of the weight of the tape itself when it is suspended between two points during measurement. When a tape measure is stretched between two points over a distance, especially if the tape is long, it can sag due to its weight. This sagging can cause the measured distance to appear longer than the actual horizontal distance between the two points.

The sag correction is, therefore, a negative correction because it compensates for this excess measurement. By applying this correction, surveyors can adjust the measured distance to reflect the true horizontal distance. This is crucial for achieving high accuracy in surveying, where precision is paramount.