Lateral Area Calculator
Just the Sides, Not the Caps
Lateral area strips out the top and bottom faces of a solid and measures only the area that wraps around its side — the label on a can, not the two circular ends. For cylinders and cones, that curved surface unrolls into a flat, calculable shape once you know the radius and either the height or the slant height.
The Formulas
Right Cylinder: Lateral Area = 2πrh
Right Circular Cone: Slant Height (l) = √(r²+h²), Lateral Area = πrl
Right Circular Cone: Slant Height (l) = √(r²+h²), Lateral Area = πrl
Worked Examples
Using radius 3 and height 8 for both shapes:
| Shape | Key Step | Lateral Area |
|---|---|---|
| Cylinder | 2 × π × 3 × 8 | 150.7964 |
| Cone | slant l = √(3²+8²) = 8.544; π × 3 × 8.544 | 80.5253 |
The cone's slant height is longer than its vertical height, which is why its lateral area doesn't simply track the cylinder's.
Where This Matters
- Labeling and wrapping — the flat material needed to wrap around a can, tube, or cone-shaped container.
- Paint and coating estimates — coating only the curved side of a silo or tank (excluding top/bottom) uses lateral area, not total surface area.
- Sheet metal fabrication — rolling flat stock into a cylindrical or conical shell starts from the unrolled lateral area.
How to Use This Calculator
- Choose the shape: Right Cylinder or Right Circular Cone.
- Enter the Radius.
- Enter the Height.
- Select Calculate to get the lateral (side-only) area.
Related Calculations
Need the full surface including top and bottom? See the Surface Area Calculator, or find the enclosed volume with the Cylinder Volume Calculator.