Triangle Area Calculator

Choose a method — Base & Height, Two Sides & Angle, or Three Sides — to calculate a triangle's area.

How to Use the Triangle Area Calculator

Three modes cover the three ways a triangle's area actually gets measured in practice: Base & Height, Two Sides & Angle (SAS), and Three Sides (SSS). Pick whichever matches the measurements on hand.

Base & Height:      area = ½ × base × height
Two Sides & Angle:  area = ½ × a × b × sin(C)
Three Sides:        area = √(s(s−a)(s−b)(s−c)),  s = (a+b+c) ÷ 2

Base & Height is the version taught first, but it needs a perpendicular height that isn't always easy to measure directly. The SAS version sidesteps that by trading the height for an angle — useful whenever a protractor is easier to reach for than a plumb line. The SSS version (Heron's formula) needs neither a height nor an angle, only three tape-measure readings, at the cost of a slightly heavier calculation.

All three return the same area for the same triangle, since they're just three different ways of encoding the same shape — the mode picker exists purely because the input measurements available rarely offer a choice.