What is a surface area calculator?
A surface area calculator computes the total area of all surfaces of a three-dimensional shape. Surface area is measured in square units—square meters, square feet, square inches—and represents the amount of material needed to cover the shape or the area exposed to the environment (e.g. for heat transfer or coating). This calculator supports five common 3D shapes: cube, sphere, cylinder, cone, and rectangular prism. You select a shape, enter the required dimensions (side length, radius, height, etc.), and the tool gives you the total surface area and the formula used. No sign-up or download is required; it runs in your browser and is useful for homework, engineering, construction, and any task where you need to find how much surface a 3D object has.
Understanding surface area is essential whenever you need to cover, paint, wrap, or insulate a solid, or when comparing heat loss or exposure across different shapes. This free surface area calculator uses the same units you enter: if your dimensions are in meters, the result is in square meters; if in feet, the result is in square feet. Keep all measurements in one unit for consistent results.
How to use this surface area calculator
First, choose the 3D shape from the dropdown: Cube, Sphere, Cylinder, Cone, or Rectangular Prism. The input fields update to match the shape. For a cube, enter the side length. For a sphere, enter the radius. For a cylinder or cone, enter radius and height. For a rectangular prism, enter length, width, and height. All values must be positive numbers. When the inputs are valid, click Get result to see the surface area in square units and the formula used. The calculator shows both a short formula (e.g. 6 × side²) and the numerical evaluation so you can verify or learn the relationship. Change the shape or dimensions anytime and click Get result again for a new calculation.
Surface area formulas by shape
Cube: Surface area = 6 × side². A cube has six identical square faces, each with area side². Sphere: Surface area = 4π × radius². The sphere has a single curved surface; there is no “base” or “top.” Cylinder: Surface area = 2π × radius × (radius + height). This is the sum of the areas of the two circular bases (2 × πr²) and the curved lateral surface (2πrh), which simplifies to 2πr(r + h). Cone: Surface area = π × radius × (radius + slant height), where slant height = √(radius² + height²). The cone has one circular base and one curved lateral surface. Rectangular prism: Surface area = 2 × (length × width + length × height + width × height). The prism has six rectangular faces in three pairs of opposite sides. This surface area calculator applies the correct formula for the shape you select.
Surface area vs volume
Surface area measures the total area of all outer surfaces (a 2D measure in square units). Volume measures the amount of 3D space inside the solid (in cubic units). For example, a cube with side 2 has surface area 6 × 4 = 24 square units and volume 2³ = 8 cubic units. Surface area is used when you need to cover the object—paint, wrapping, insulation, coating. Volume is used when you need to know capacity—how much fits inside. The two are related but different: doubling the side of a cube multiplies surface area by 4 and volume by 8. This calculator focuses on surface area; use a volume calculator for volume.
Common surface area examples
Cube: Side 3 → surface area 6 × 9 = 54 square units. Sphere: Radius 2 → surface area 4π × 4 ≈ 50.27 square units. Cylinder: Radius 2, height 5 → surface area 2π × 2 × (2 + 5) = 4π × 7 ≈ 87.96 square units. Cone: Radius 3, height 4 → slant = 5, surface area π × 3 × (3 + 5) ≈ 75.40 square units. Rectangular prism: Length 4, width 3, height 2 → surface area 2 × (12 + 8 + 6) = 52 square units. You can enter these values in the calculator to verify and see the formulas in action.
Units and consistency
Surface area is always in square units of whatever linear unit you use. If you enter dimensions in meters, the surface area is in square meters (m²). If you enter in feet, it is in square feet (ft²). If you enter in inches, it is in square inches (in²). Never mix units in one calculation. Convert your dimensions to the desired unit before entering, or convert the result afterward using an area converter. The calculator does not convert between units; it assumes consistent input.
Applications of surface area calculations
Surface area is used in construction (paint, siding, roofing), manufacturing (coating, packaging material), engineering (heat transfer, corrosion protection), chemistry (reaction surface), and design (material estimates). Whenever you need to know how much material covers a 3D object—or how much area is exposed to the environment—you use surface area. This surface area calculator gives you instant results for five common 3D shapes so you can focus on measuring accurately and applying the numbers to your project.
Tips for accurate surface area results
Measure dimensions with a ruler, tape measure, or calipers as appropriate. For cubes and rectangular prisms, measure length, width, and height along the edges. For spheres, cylinders, and cones, measure the radius (from center to edge) or diameter/2, and for cylinder/cone measure the height perpendicular to the base. Ensure all values are positive and in the same unit before clicking Get result. The calculator shows the formula and the numerical result so you can double-check. Accurate inputs give accurate surface areas.
Summary
This surface area calculator finds the total surface area of cubes, spheres, cylinders, cones, and rectangular prisms. Select a shape, enter the required dimensions in the same units, and click Get result to see the surface area in square units and the formula used. The tool is free, runs in your browser, and requires no account. Use it for homework, engineering, construction, or any calculation involving 3D shape surface areas. Keep units consistent and measure carefully for best results.