Sphere Surface Area Calculator
SA = 4πr². Exactly 4× the area of a great circle of the same radius.
Result
How to use this calculator
- Enter radius.
- Read SA + great-circle area + volume.
About this calculator
Sphere surface area = 4πr², exactly four times the area of a great circle (a cross-section through the center). Archimedes proved this around 250 BCE — and was so proud he had it engraved on his tomb. Earth's surface ≈ 4π × (6371 km)² ≈ 5.1 × 10⁸ km². The sphere has the smallest surface area of any closed surface enclosing a given volume — why bubbles are spherical.
Frequently asked
Why 4× great circle?+
Earth surface area?+
Hemisphere?+
Why is sphere optimal?+
Real-world spherical SA?+
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