This online calculator computes the surface area of a sphere from any one of: radius r, diameter d, or great-circle circumference c. Displays all related values (A, r, d, c) consistently.

Sphere Surface Area Calculator

Enter only one parameter: radius r, diameter d or great-circle circumference c. The tool computes area A and shows r, d, c on the diagram.

Sphere visualization

Radius (r)

or

Diameter (d)

or

Circumference (c)

Surface Area (A)

Calculation details will appear here.
Decimal Places
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How to use

  1. Enter one value: radius r, or diameter d, or circumference c. (If you enter several, the calculator uses r → d → c priority and warns on inconsistency.)
  2. Click Calculate. The tool outputs surface area A and shows r, d, c on the visualization.
  3. Adjust Decimal Places (0–8) to control rounding; the internal computation uses full precision.
  4. Use Copy Result to copy A for reports or further work.

Formulas and relations

  • A = 4·π·r²
  • d = 2·r
  • c = 2·π·r

Equivalently, from other inputs:

  • From d: A = π·d²
  • From c: A = c²/π
  • Conversions: r = d/2 = c/(2·π)

Sources: Wolfram MathWorld — Sphere, NIST DLMF §4.3.

Area of a Sphere Calculator Online

Vizualisation of a sphere with parameters

Inputs and units

All linear inputs (r, d, c) use the same unit (mm, cm, m, in, ft, etc.). The area result A is reported in the corresponding squared unit (mm², cm², m², in², ft², etc.).

Example calculations

  1. Given r = 4 cm → A = 4·π·4² = 64·π ≈ 201.0619 cm²; d = 8 cm; c = 2·π·4 ≈ 25.1327 cm.
  2. Given d = 1.2 m → A = π·(1.2)² ≈ 4.5239 m²; r = 0.6 m; c = 2·π·0.6 ≈ 3.7699 m.
  3. Given c = 10 in → r = c/(2·π) ≈ 1.5915 in; d ≈ 3.1831 in; A = c²/π ≈ 31.83099 in².

Accuracy and rounding

  • π is taken from the runtime environment with double precision.
  • Displayed values are rounded to the chosen decimal places; intermediate steps use full precision to reduce rounding error.
  • If you supply multiple inputs that disagree beyond numeric tolerance, the calculator flags the mismatch and proceeds using the highest-priority field.

When to use this calculator

  • Geometry homeworks and exams (quick checks of sphere relations).
  • Engineering and fabrication (coatings, surface treatments, material estimates).
  • 3D graphics, simulation, and game asset specs (area-dependent effects).
  • Science labs (surface-related phenomena such as heat transfer or diffusion models).

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