The length of the [[formation]] interval over which a depth-related [[correlation]] is made in order to determine the depth wise [[displacement]] between [[curve|curves]] on which the same geological events have been logged. The correlation length is an important parameter in the computation of [[dipmeter]] measurements. Dipmeter log correlations are made in order to evaluate the displacements between the correlation curves; these displacements are used in turn in the calculation of the formation [[dip]].

The correlation length used will depend on the purpose. Long correlation lengths (10 to 20. or even 30 feet are used for evaluating structural dip. Short correlation lengths (1, 2, or 3 feet) are useful in determining finer details of the dip for sedimentation studies over such stratigraphic features as bars, lenses or [[channel|channels]].