Surface Area of a Sphere Formula Explained, With Examples
Every surface area of a sphere result comes from one formula. Once you understand what goes into it, you can sanity-check any figure you are given, whether by an employer, a bank, a teacher or another website.
The formula
4πr²
What each input means
- Radius: the value you enter in the calculator.
Example
For example, with these inputs:
- Radius: 5
the calculator returns:
- Surface area: 314.1593
How the result changes
The table keeps the other inputs at their example values and changes radius.
| Radius | Surface area |
|---|---|
| 5 | 314.1593 |
| 2.5 | 78.5398 |
| 3.75 | 176.7146 |
| 6.25 | 490.8739 |
| 7.5 | 706.8583 |
Why it matters
These calculations come up in school, at work and in daily life, from PSLE and O-Level practice to measuring a room for new flooring. Doing them by hand builds understanding, and a calculator lets you check the answer instantly.
These calculations appear throughout the Singapore syllabus, from primary school percentages and fractions to secondary school algebra and geometry. Understanding the formula makes problem sums easier because you can recognise which quantity is missing.
Rounding is a common source of small errors. Keep full precision during intermediate steps and round only the final answer to the number of decimal places or significant figures the question asks for.
A quick mental estimate before calculating is a powerful check. If a room's floor area comes out at 4,000 square metres or a percentage comes out above 100% when it should not, you know to look again.
Related calculations
- Percentage Change Calculator: Calculates the percentage increase or decrease.
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- Percentage Decrease Calculator: Subtracts a percentage from a number.
- Percentage Difference Calculator: Compares two values relative to their average.
Use the Surface Area of a Sphere Calculator to plug in your own numbers.
Run your own numbers: Surface Area of a Sphere Calculator