円面積計算機

衛星マップで円を描いて面積と半径を即座に測定。エーカー、ヘクタール、平方フィートなどで結果を表示。

読み込み中...

手動半径

ヒント

  • 1.マップをクリックして中心点を設定
  • 2.もう一度クリックして半径を設定するか、手動で入力
  • 3.面積と円周は即時計算されます
  • 4.検索バーで任意の場所に移動できます

Frequently Asked Questions

How is circle area calculated on a map?

The circle area is calculated using the standard formula A = πr², where r is the radius measured as the great-circle distance between the center point and edge point on the Earth surface. This accounts for the curvature of the Earth for large circles.

What units can I measure circle area in?

You can view circle area in square meters, square kilometers, hectares, acres, square feet, and square miles. The radius and circumference can be displayed in meters, kilometers, feet, or miles.

Can I use this for center-pivot irrigation planning?

Yes! Center-pivot irrigation systems create circular fields. Enter the pivot arm length as the radius to calculate the irrigated area. A typical quarter-mile (402m) pivot irrigates about 125-130 acres (50.5 hectares).

How accurate is the map measurement?

Map measurements use the WGS84 ellipsoid model and are accurate to within a few meters for circles under 10 km radius. For very large circles, the spherical approximation may introduce small errors.

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