Triangular Prism Calculator: Volume and Surface Area
Enter the three sides of the triangle at each end and how long the prism is. You get the volume and surface areas with steps.
- Nothing you type is stored
- Free
- No signup
Volume
60cm³
- Triangle end area (B)
- 6 cm²
- Lateral surface area (LSA)
- 120 cm²
- Total surface area (TSA)
- 132 cm²
Show working
- s = (a + b + c) / 2 = 6
- B = √(s(s−a)(s−b)(s−c)) = 6 cm²
- V = B × L = 6 × 10 = 60 cm³
- LSA = (a + b + c) × L = 120 cm²
- TSA = LSA + 2B = 132 cm²
How to use
- Enter triangle sides a, b and c.
- Enter the prism length L and pick a unit.
- Read the volume, base area, LSA and TSA.
Good to know
The triangular end's area B comes from Heron's formula (NCERT Class 9), so you do not need its height. Volume = B × L.
Lateral surface area = perimeter of the triangle × length = (a + b + c) × L, the three rectangular faces. Total surface area adds both triangular ends: LSA + 2B.
A 3-4-5 right triangle with length 10 gives B = 6, volume = 60 and TSA = 132. Tent shapes, roof sections and glass prisms are common examples.
Questions
What is the volume of a triangular prism?
Area of the triangular end × length of the prism.
What if I know the triangle's base and height instead?
Then B = ½ × base × height. You can enter that area directly in the volume calculator's prism option.
What is the lateral surface area of a prism?
Perimeter of the base × length: the area of the rectangular sides.
Why does it say the sides cannot make a triangle?
Any two sides must add up to more than the third. Check the measurements.
Is anything I enter stored?
No. The calculation runs in your browser and nothing is sent to a server.