Apparent Dip Calculator

Apparent dip is the dip you observe in a section that is not cut perpendicular to strike. Only a section running directly down the true dip direction shows the full dip; any other direction shows a shallower angle. In geosteering this matters because the wellbore is a section, and the dip seen along it is almost never the true stratigraphic dip.

tan(apparent dip) = tan(true dip) × cos(Δazimuth), where Δazimuth is the angle between the section direction and the true dip direction. To go the other way, divide instead of multiply: tan(true dip) = tan(apparent dip) ÷ cos(Δazimuth).

If you interpret the dip seen along the wellbore as the true structural dip, you will misplace the formation and steer to the wrong target. A 30° true dip seen along a section 60° off the dip direction appears as only 16.1°. Correcting for the azimuth difference is what keeps the geological model consistent with the wellbore observations.

When the section direction is 90° from the true dip direction, cos(Δazimuth) is zero, so the apparent dip is zero regardless of how steep the true dip is — the beds appear flat. The conversion cannot be reversed in that case: no apparent dip measurement along strike can tell you the true dip, and this calculator will say so rather than return a misleading number.