Volume of a Triangular Prism Calculator

The volume is V = A × L, where A is the area of the triangular base and L is the prism length (the distance between the two triangular faces). If you know the triangle's base b and height h, then A = ½ × b × h. Example: base 6 cm, height 4 cm, length 10 cm gives A = ½ × 6 × 4 = 12 cm², so V = 12 × 10 = 120 cm³.

Use Heron's formula. First compute the semiperimeter s = (a+b+c)/2, then the area A = √(s(s−a)(s−b)(s−c)). Example: sides 5, 6, 7 cm with prism length 9 cm gives s = 9, A = √(9×4×3×2) = √216 = 14.696938 cm², so V = 14.696938 × 9 = 132.272446 cm³.

Yes. It handles right, isosceles, equilateral, and scalene triangles, in either mode. The 3-sides mode validates the triangle inequality and rejects impossible sets such as 2, 3, 10. Example: the 13-14-15 scalene triangle with length 12 cm gives A = 84 cm² and V = 1008 cm³.

S = 2A + P × L, where P is the perimeter of the triangular base: the two triangular faces plus the three rectangular side faces. This needs all three side lengths, so use the 3-sides mode. Example: 13-14-15 with length 12 cm gives S = 2 × 84 + 42 × 12 = 672 cm².

The base shape: a triangular prism has a 3-sided triangle base (volume V = A_triangle × L), while a trapezoidal prism has a 4-sided trapezoid base with two parallel sides (volume V = ((a+b)/2 × h) × L). Use this calculator for triangle bases; for trapezoid bases use a trapezoidal prism volume calculator.

Any consistent length unit: millimeters, centimeters, meters, inches, or feet. The base area comes out in square units and the volume in cubic units (for example, cm, cm², cm³).

Yes. Every result shows its full working: the semiperimeter and Heron product when you use the 3-sides mode, the ½ × base × height step in base-height mode, then V = A × L, and the surface-area breakdown S = 2A + P × L when the sides are known.

Yes, it is free, and it runs 100% in your browser. No inputs are sent to any server; there are no external requests, accounts, or tracking in this tool.