Triangle Area Calculator
Find the area of a triangle from its base and height — fast, accurate, and with no manual math.
Formula
S = ½ · a · h
a is the base of the triangle, h is the height drawn to that base.
About the triangle area calculator
The area of a triangle is the size of the region enclosed by its three sides. The easiest way to find it is to multiply the base by the height and divide by two.
The height must be drawn to the base you entered: it is the perpendicular distance from the opposite vertex to the line containing that base. The base and height must use the same unit.
Every calculation runs instantly and entirely in your browser — nothing is uploaded, so your numbers stay completely private.
Benefits
Instant results
The area updates immediately as you type the base and height.
Accurate formula
Uses the classic S = ½ · a · h formula with no hidden rounding.
Fully private
All math happens locally in your browser; nothing is sent to a server.
Frequently asked questions
How do I calculate the area of a triangle from base and height?
Multiply the base by the height and divide by two: S = ½ · a · h. The calculator does this for you automatically.
What counts as the height of a triangle?
The height is the perpendicular dropped from a vertex to the base (or its extension). It must match the base you selected.
What unit will the area be in?
If the base and height are in centimeters, the area is in square centimeters (cm²). The base and height must share the same unit.
Does this formula work for any triangle?
Yes, S = ½ · a · h works for any triangle — acute, right, or obtuse — as long as you know a base and the height drawn to it.
Can I enter decimal values?
Yes, you can enter decimals such as 12.5. The calculator handles fractional bases and heights correctly.