Free Surface Area Calculator Online
This free online surface area calculator computes total and lateral surface area for common 3D shapes — cubes, spheres, cylinders, cones, and rectangular prisms.
Shape & Dimensions
Total Surface Area
Select shape and enter dimensions
How the Surface Area Calculator Works
Select a 3D shape, enter its dimensions, and the surface area calculator instantly computes the total surface area, lateral surface area, and volume. The surface area calculator supports five shapes: cube, rectangular prism, sphere, cylinder, and cone.
For a cube with side 4: surface area = 6 × 4² = 96 square units. For a sphere with radius 3: surface area = 4π × 9 ≈ 113.1. The surface area calculator applies the correct formula based on your selected shape.
The surface area calculator also computes volume alongside surface area. This is useful for comparing shapes — a sphere has the smallest surface area for a given volume, which is why bubbles and planets are spherical.
Surface Area Formulas
Cube (side a)
SA = 6a²
Rectangular Prism (l, w, h)
SA = 2(lw + lh + wh)
Sphere (radius r)
SA = 4πr²
Cylinder (r, h)
SA = 2πr² + 2πrh
Cone (r, h)
SA = πr² + πr√(r²+h²)
Tips for Using the Surface Area Calculator
Choose the Right Shape
Select the shape that matches your object. The surface area calculator adjusts the input fields and formula accordingly.
Total vs. Lateral
Total surface area includes bases; lateral excludes them. Use lateral for paint coverage on cylindrical tanks (no top/bottom). The surface area calculator shows both.
Consistent Units
Use the same unit for all dimensions. Surface area is in squared units (cm², m², ft²). The surface area calculator is unit-agnostic.
Also Gets Volume
The surface area calculator also computes volume for each shape, so you get both measurements from a single entry.
Frequently Asked Questions
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