Apparent Dip Calculator
Enter a plane's true dip and strike, plus the direction of your cross-section or cliff face, to get the apparent dip you would measure in that section. Free, in your browser.
Apparent dip
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Angle from strike (β)
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What is apparent dip?
The true dip is the steepest angle of a tilted plane, measured perpendicular to strike. But when you look at that plane in a road cut, a cliff face, or a cross-section that is oblique to strike, it appears to dip at a gentler angle — the apparent dip.
tan(apparent dip) = tan(true dip) × sin(β)
β = horizontal angle between the line of section and the strike
Two limits make it intuitive: a section taken perpendicular to strike (β = 90°) shows the full true dip, while a section running along strike (β = 0°) shows no dip at all. Apparent dip is always ≤ true dip.
Measured the plane in the field first? Use the strike & dip converter to switch notations, or plot it on the stereonet. New to strike and dip? Start with our measurement guide.
Apparent dip FAQ
What is apparent dip?
Apparent dip is the dip angle of a plane as seen in a vertical cross-section that is not perpendicular to strike. It is always ≤ the true dip, and equals the true dip only when the section is exactly perpendicular to strike.
What is the apparent dip formula?
tan(apparent dip) = tan(true dip) × sin(β), where β is the horizontal angle between the line of section and the strike. β = 90° gives the true dip; β = 0° (along strike) gives 0.
Why is apparent dip smaller than true dip?
Any cross-section oblique to strike cuts the plane at a gentler angle than a section perpendicular to strike. The more the section swings toward the strike direction, the shallower the apparent dip.
Capture the real dip in the field
GeoKit measures true strike & dip in one step and plots your structure automatically — free, offline, on iOS & Android.
