Triangle Area Calculator

Formula

From base and height: area = ½ × base × height. From three sides a, b, c: first di semiperimeter s = (a + b + c) ÷ 2, then Heron formula, area = √(s(s − a)(s − b)(s − c)). Di two methods go agree whenever di height match di sides; you fit use each one check di other. Di three sides must satisfy triangle inequality: each side must short pass di sum of di other two. Otherwise, no triangle dey.

Example wey show the calculation

Base na 10 and height na 6: area = ½ × 10 × 6 = 30. For di 3–4–5 triangle: s = (3 + 4 + 5) ÷ 2 = 6, so area = √(6 × 3 × 2 × 1) = √36 = 6, and di perimeter na 3 + 4 + 5 = 12. Di 3–4–5 triangle get right angle (3² + 4² = 5²), so im area still equal ½ × 3 × 4 = 6. Na third way to get di same answer be dat.

Where e fit work and limits

Dis page only dey calculate area; e no dey find missing sides or angles. Di right-triangle calculator dey handle sides and angles for right triangles. Heron formula need all three sides and valid triangle: if any side na zero or negative, or di sides fail triangle inequality, di page go tell you instead of showing square root of negative number. Results dey use di square of whichever length unit you enter; dis page no dey convert units.

Version of di formula: e47974748398 · Example don get check: 2026-10-31

Questions wey people dey ask often

Why na half of base times height?

Because triangle na half of parallelogram wey get di same base and height. Two copies of di triangle go form di parallelogram, wey im area na base × height. Half of dat na di triangle.

When I go use Heron formula?

When you know di three sides but no know di height; for example, land wey you measure along im three boundaries. If you know one base and im height, di simpler formula go do.

Wetin be semiperimeter?

Na half di perimeter: s = (a + b + c) ÷ 2. Heron discover say di area depend only on s and how much each side short from am. For 3–4–5, s = 6, and di shortfalls na 3, 2 and 1.

Wetin if di sides no fit form triangle?

Then di sides no satisfy triangle inequality. For example, sides 1, 2 and 10 no fit form triangle because 1 + 2 small pass 10. Di page go report say no such triangle dey instead of showing meaningless number.

Di two methods dey always agree?

For real triangle, yes, so long as di height belong to di base wey you enter. If base-height area and Heron area no agree, one input no match. Most times, na height wey dem measure for another base.

Dis one dey work for every triangle type?

Yes: acute, right, obtuse, isosceles and equilateral triangles all dey use di same two formulas. Equilateral triangles get shortcut (area = √3 ÷ 4 × side²), but Heron formula go give di same result.

Other tools wey relate to dis

• Calculator for circle — area, circumference and diameter from radius
• Calculator for square area — area and perimeter of rectangle
• Converter for area units — square metres, feet, acres and more