01
How to use this calculator
- Choose a solid shape from the shape selector.
- Enter its dimensions in one consistent unit.
- Calculate the total outer surface area and review the substituted formula.
02
A little understanding goes a long way.
Surface area measures the exterior of a three-dimensional object in square units. Total area includes bases and ends. Lateral area covers the sides without bases.
THE FORMULA
Rectangular prism: A = 2(lw + lh + wh)
TRY IT ON PAPER
A worked example
A rectangular prism measuring 4 m × 3 m × 2 m has surface area 2(12 + 8 + 6) = 52 m².
03
A few common questions
Which shapes are supported?
Cube, rectangular prism, sphere, closed cylinder, right circular cone and right triangular prism.
Does a cylinder include both ends?
Yes. Total area includes the curved side and two circular ends. The result also gives lateral area separately.
Does the cone use height or slant height?
Enter vertical height. The calculator finds slant height using √(radius² + height²), then includes the circular base.