Finds the total surface area of a triangular prism — the two triangular ends plus the three rectangular sides wrapped around its length.
How it works
Twice the triangle’s area is added to the triangle’s perimeter multiplied by the prism’s length.
What this does not include
This does not include the prism’s volume — for that, use this site’s triangular prism volume calculator instead.
How to use this calculator
- Enter the triangle’s base, height, and other two sides, plus the prism’s length.
A worked example
A triangular prism with triangle base 6, height 4, two equal sides of 5, and prism length 10: total surface area = 184.
Base 3, height 4, sides 5 and 4.2426, length 5: surface area = 73.213.
What the variables mean
| Variable | Meaning |
|---|---|
| Base, triangle height | The triangular cross-section’s base and height |
| Side B, Side C | The triangle’s other two sides, needed for the rectangular face areas |
| Length | How far the triangle is extruded to form the prism |
Edge cases worth knowing
Surface area needs all three triangle sides, unlike volume, which only needs base and height. The three rectangular faces of the prism each depend on a different side length, so skipping any of them understates the total.
A base of zero collapses the triangular cross-section entirely, leaving no prism to measure, so the calculator declines to show a result.
Frequently asked questions
Why do I need all three triangle sides?
The base and height give the triangle’s area, but the perimeter (needed for the three rectangular side faces) requires all three side lengths.
What’s a real-world example of a triangular prism?
A tent, a Toblerone chocolate bar, or a road wedge — any solid with a constant triangular cross-section extended along a length.
Does a right triangle prism use a different formula?
No — the same formula applies to any triangular cross-section; a right triangle is simply a special case where one side happens to be perpendicular to another.
