Triangle Area Calculator

Calculate the area of any triangle using base and height. Also computes hypotenuse length and perimeter for right triangles.

Triangle Calculator
Triangle Area
40.00
sq ft
In Sq Meters
3.72
sq m
Hypotenuse
12.81
ft
Perimeter
30.81
ft

What is Triangle Area Calculator?

A triangle area calculator computes the area of any triangle using the base and perpendicular height. The triangle is the simplest polygon and one of the most common shapes in construction, architecture, and design.

This tool exists because triangular areas appear everywhere — gable walls, roof sections, angled corners in rooms, decorative features, and land parcels. The formula (½ × Base × Height) is simple, but this calculator also provides the hypotenuse length and perimeter, saving you additional manual calculations.

The height must be measured perpendicular to the base — at a 90° angle. For right triangles, one leg is the base and the other leg is the height. For non-right triangles, drop a perpendicular from the apex to the base.

Triangle Area Calculator Formula

Area = ½ × Base × Height

Example: Base = 10 ft, Height = 8 ft. Area = ½ × 10 × 8 = 40 sq ft (3.72 sq m).

Hypotenuse (for right triangles): √(Base² + Height²) = √(100 + 64) = √164 = 12.81 ft.

Perimeter: Base + Height + Hypotenuse = 10 + 8 + 12.81 = 30.81 ft.

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Frequently Asked Questions

What is the formula for triangle area?
Area = ½ × Base × Height. The base is any side of the triangle. The height is the perpendicular distance from the base to the opposite vertex. For a triangle with base 10 ft and height 8 ft: Area = ½ × 10 × 8 = 40 sq ft.
How do I find the height of a triangle?
If you know the area and base: Height = 2 × Area ÷ Base. If you know two sides and an included angle: Height = Side × sin(angle). For a right triangle, the height is the side perpendicular to the base.
What is the hypotenuse of a right triangle?
The hypotenuse is the longest side of a right triangle, opposite the 90° angle. Calculate it using the Pythagorean theorem: Hypotenuse = √(Base² + Height²). For base 6 and height 8: Hypotenuse = √(36 + 64) = √100 = 10.
How do I calculate the area of an equilateral triangle?
For an equilateral triangle with side s: Area = (√3/4) × s². For a side of 10 ft: Area = (1.732/4) × 100 = 43.30 sq ft. The height of an equilateral triangle is s × √3/2.
How do I calculate the perimeter of a triangle?
Perimeter = Side1 + Side2 + Side3. For a right triangle with base b and height h: the hypotenuse is √(b² + h²), so Perimeter = b + h + √(b² + h²). For base 6 and height 8: P = 6 + 8 + 10 = 24.