How to find the area of a triangle in square feet
Multiply the base by the height and divide by 2, with both in feet. A triangle with a 12 ft base and an 8 ft height covers 12 × 8 ÷ 2 = 48 square feet. If you only know the three sides, the calculator uses Heron's formula instead.
Formula
Area (sq ft) = base (ft) × height (ft) ÷ 2
Cubic yards = area (sq ft) × depth (in) ÷ 324
1 cubic yard = 27 cubic feet (3 ft × 3 ft × 3 ft)
Worked example
triangle, 12 ft base × 8 ft height, 3 in deep
- Find the area: 12 ft × 8 ft ÷ 2 = 48 sq ft.
- Convert the depth to feet: 3 in ÷ 12 = 0.25 ft.
- Multiply by the depth: 48 sq ft × 0.25 ft = 12 cubic feet.
- Divide by 27: 12 ÷ 27 = 0.44 cubic yards.
Using the three side lengths
When there is no easy way to measure a height at a right angle, measure all three sides and use Heron's formula: add the sides and halve the total to get s, then area = √(s × (s − a) × (s − b) × (s − c)). Sides of 10, 10 and 12 feet give s = 16 and an area of √(16 × 6 × 6 × 4) = 48 square feet.
The three sides must form a real triangle: any two of them added together must be longer than the third.
From square feet to cubic yards
Multiply the area by the depth in inches and divide by 324. The 48 sq ft triangle covered 3 inches deep needs 48 × 3 ÷ 324 = 0.44 cubic yards.
How far one cubic yard spreads, and how much you need for every 100 square feet, at common depths.
Square feet, square yards and acres
One square yard is 9 square feet and one acre is 43,560 square feet. The calculator shows all three. Sod is sold by the square foot, so the square-foot result is the number to order.
Frequently asked questions
Does the base × height method work for any triangle?
Yes, as long as the height is measured at a right angle from the base to the opposite corner. If that is hard to measure on the ground, use the three sides instead.
How do I find the cubic feet of a triangle?
Multiply the area in square feet by the depth in feet. A 48 sq ft triangle 6 inches (0.5 ft) deep is 24 cubic feet, or 0.89 cubic yards.
How do I convert a triangle's square feet to acres?
Divide the square feet by 43,560. A 4,356 sq ft triangle is 0.1 acre.
How many cubic feet are in a cubic yard?
27. Divide cubic feet by 27 to get cubic yards.
Order by the cubic yard
Soil Direct delivers bulk landscape materials by the cubic yard from local suppliers. Enter your address to see delivered prices.
Link to or cite this page
Teachers, writers, landscapers and anyone else are welcome to link to or cite this page. Please credit Soil Direct.
Citation
Soil Direct. "Triangle Area Calculator." soildirect.com, 2026. https://soildirect.com/calculator/triangle-calculator/
Link HTML
Triangle Area Calculator by <a href="https://soildirect.com/calculator/triangle-calculator/">Soil Direct</a>