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Surface Area Calculator
Find the surface area of a cube, rectangular prism, cylinder, sphere, cone, or square pyramid.
Length of every edge. Zero is allowed.
Labels the results, such as cm or in. Area is shown with that unit squared. Nothing is converted.
Formula
SA = 6a²
Enter a side length to see 6a² with your number, then the surface area.
This surface area calculator finds the total outside area of a cube, rectangular prism, cylinder, sphere, cone, or square pyramid. Enter the lengths for that shape and the page substitutes them into the standard formula: 6a² for a cube, 2(lw + lh + wh) for a rectangular prism, 2πr(h + r) for a cylinder, 4πr² for a sphere, and πr(r + l) for a cone, with slant height l = √(r² + h²). A cylinder also lists the lateral area 2πrh, and a cone or square pyramid shows the slant height computed from the height you entered. Type a unit such as cm or in to label the answer; the tool does not convert units.
How to find surface area
Surface area is the total area of the outside of a solid. Choose a shape, enter its lengths, and the calculator writes the formula with those numbers in place. A cube is 6a², so a side of 3 has surface area 54. A sphere is 4πr², so a radius of 3 has surface area 36π.
The surface area of a cylinder is 2πr(h + r), the lateral area 2πrh plus the two circular bases. A radius of 2 and a height of 5 has total surface area 28π and lateral area 20π. A rectangular prism is 2(lw + lh + wh), and a cone is πr(r + l), where the slant height l is √(r² + h²).
Frequently Asked Questions
What is the surface area of a cylinder?
The total surface area is 2πr(h + r), the same as 2πr² + 2πrh. The lateral area, just the curved side, is 2πrh. A radius of 2 and a height of 5 has lateral area 20π and total surface area 28π, about 87.964594.
How do you find the surface area of a cube?
A cube has six square faces, so the surface area is 6a². A side of 3 has face area 9 and total surface area 54. A side of 0 collapses the cube to a point; the formula is still defined and equals 0.
What is the surface area of a sphere?
The surface area of a sphere is 4πr². A radius of 3 has surface area 36π, about 113.09734. A sphere has no separate base, so there is no lateral area to add.
How do you find the surface area of a rectangular prism?
Add the three different face areas and double that sum: 2(lw + lh + wh). A length of 4, a width of 3, and a height of 2 is 2(12 + 8 + 6), which is 52. A height of 0 flattens the prism; the formula is still defined.