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MATH & SCIENCE

Find the Height of a Building — Trigonometry

Find a building’s height from a measured distance and angle of elevation.

About this tool

Solve the classic "how tall is that building" trigonometry problem — given a horizontal distance and an angle of elevation, find the height, or work backward from any two of the three to find the missing one.

This is a right-triangle problem: the angle of elevation is measured from the horizontal up to the object, the horizontal distance is one leg of the triangle, and the height is the other leg — related by the tangent function (height = distance × tan(angle)). Angle of depression works identically, just measured downward from horizontal instead of upward (like looking down at a boat from a cliff), and uses the exact same math.

This assumes you're measuring from eye level or ground level in a flat, simple setup — real surveying accounts for the observer's own height and more complex terrain, but the core trigonometry is exactly the same relationship.

Frequently asked questions

What’s the difference between elevation and depression?

Elevation is the angle measured upward from horizontal (looking up at something), depression is measured downward (looking down at something) — they use identical trigonometry, just describing which direction you’re looking.

Does this account for my own height as the observer?

Not automatically — it calculates the height above your eye level or instrument level, not above the ground. Add your own height to the result if you need the total height above ground.

Why tangent, and not sine or cosine?

Tangent relates the two legs of a right triangle directly (opposite over adjacent) without needing the hypotenuse at all — exactly the two measurements (height and horizontal distance) this kind of problem usually starts with.

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