Area of a Frustum of a Cone Calculator

Find the lateral and total surface area of a cone frustum.

Lateral area 207.25

Total surface area 314.06

Formula: lateral = π(R + r)·slant; total adds both circles

Step-by-step with your numbers:

1. Values used:

2. Bottom radius = 5

3. Top radius = 3

4. Height = 8

6. Lateral area = 207.25

7. Total surface area = 314.06

Did we solve your problem today?

Find the surface area of a frustum — the side plus the two circular ends.

The math behind it

Lateral area = π(R + r)·slant, with slant = √(h² + (R − r)²). The total adds the two circle areas πR² and πr².

R = 5, r = 3, h = 8 → lateral ≈ 207.4.

Do I include both ends?

Use lateral for the sloped side only; total includes both circular faces.