Circle Area Calculator
Calculate the area, circumference, and diameter of a circle by entering the radius or diameter. Instant results with step-by-step formulas.
How to Use the Circle Area Calculator
- Enter the required dimensions (length, width, radius, height, etc.).
- The area, volume, or other geometric value is computed instantly.
- Review the result along with the formula used.
- Adjust dimensions to compare different scenarios.
クイックリファレンス
| 変換元 | 変換先 |
|---|---|
| r = 1 | 3.14 |
| r = 2 | 12.57 |
| r = 5 | 78.54 |
| r = 10 | 314.16 |
| r = 25 | 1,963.50 |
| r = 50 | 7,853.98 |
使用例
- •Calculating dimensions for home improvement or DIY projects.
- •Solving geometry problems for school or professional exams.
- •Estimating material quantities needed for construction work.
- •Planning layouts and designs with precise measurements.
計算式
Formula: S = πr². Where r is the radius of the circle. The circumference is C = 2πr.
よくある質問
How do you calculate the area of a circle?
Multiply π (approximately 3.1416) by the square of the radius: S = πr².
Can I calculate area from the diameter?
Yes. Divide the diameter by 2 to get the radius, then use S = πr². Equivalently, S = π(d/2)² = πd²/4.
What is the circumference of a circle?
The circumference is the perimeter of a circle: C = 2πr, or equivalently C = πd.
What is π (pi)?
Pi is a mathematical constant approximately equal to 3.14159. It is the ratio of a circle's circumference to its diameter.