Triangle Area in Square Feet Calculator
Find the square footage of any triangular floor, roof section, or plot. Enter the base and perpendicular height in feet, inches, yards, metres, centimetres, or millimetres — the calculator converts and applies the ½ × base × height formula.
Unit of measurement
½ × base × height (converted to feet)
- 1
Base
20 ft - 2
Height
15 ft - 3
Area
½ × 20 × 15 = 150Triangle area = half of base times perpendicular height.
How does this calculator work?
Triangle area in square feet = ½ × base (ft) × perpendicular height (ft). Enter base and height in any unit (ft, in, yd, m, cm, mm) and the calculator gives area in sq ft, m², and acres. Works for any triangle type — only the perpendicular height matters.
Formula
How this is calculated
The area of any triangle equals half the product of its base and its perpendicular height: A = ½ × b × h. The "height" must be the perpendicular distance from the base line to the opposite vertex — for a right triangle this is simply the shorter leg; for a non-right triangle you may need to measure or calculate it separately.
The calculator converts base and height from the chosen unit to feet before applying the formula. The hypotenuse shown assumes a right triangle with the given base and height as legs (√(b² + h²)); for a non-right triangle the actual third side will differ, but the area calculation using base and perpendicular height remains correct regardless of the triangle type.
For a triangular section of a room or roof, measure the longest straight edge as the base and drop a perpendicular to find the height. Divide irregular shapes into triangles and rectangles, calculate each area, and add them.
Frequently asked questions
Area = ½ × base × height, with base and height measured in feet. For example, a triangle with a 10 ft base and 8 ft height has an area of ½ × 10 × 8 = 40 sq ft.
Use the perpendicular (vertical) height — the shortest distance from the base to the opposite corner, at a right angle to the base. For a right triangle, this is one of the two shorter sides.
Yes — the formula A = ½ × b × h works for all triangles (right, acute, or obtuse) as long as h is the true perpendicular height to the chosen base. The hypotenuse shown in the results is for reference for right triangles only.
Also known as
TG we-Calculate Editorial Team. (2026). Triangle Area in Square Feet Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/square-feet-triangle-calculator
TG we-Calculate Editorial Team. "Triangle Area in Square Feet Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/square-feet-triangle-calculator.
TG we-Calculate Editorial Team, "Triangle Area in Square Feet Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/square-feet-triangle-calculator
@misc{wecalculate_square_feet_triangle_calculator, title = {Triangle Area in Square Feet Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/square-feet-triangle-calculator}}, year = {2026}, note = {TG we-Calculate} }
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