How This Calculation Works
This calculator uses standard geometry formulas for common shapes. For 2D shapes: rectangles (L×W), circles (πr²), and triangles (½×b×h). For 3D shapes: rectangular prisms (L×W×H), cylinders (πr²h), spheres (4/3πr³), and cones (1/3πr²h).
Surface area formulas are included for 3D shapes to help with material calculations like painting or wrapping.
Common Mistakes to Avoid
- Confusing radius and diameter. The radius is half the diameter. Using diameter in a radius formula gives 4× the correct area.
- Mixing units. Make sure all measurements use the same unit before calculating. Convert everything to the same unit first.
Worked Example
Cylinder: Radius 5, Height 10.
Volume: π × 5² × 10 = 785.4 cubic units.
Surface area: 2π × 5 × (5 + 10) = 471.2 square units.