Calculate Half-Round Field
Calculator for the perimeter and size of a half-round, semicircular field, with different units. The diameter is twice the radius of the original circle. The area of a half-round is, compared to the round, half as much, whereas the perimeter is half the circumference plus the diameter. Therefore, the boundary line of this shape is larger relative to its area than that of a circle, meaning there is a larger boundary area. This can have advantages or disadvantages.
Please enter one value and choose the units. The other three values will be calculated.
Units of measurement: cm=centimeter, dm=decimeter, m=meter, km=kilometer, in=inch, ft=foot, yd=yard, mi=mile, ²,sq=square, a=are, ha=hectare, ac=acre
Formulas:
Radius r
Diameter d = 2 r
Perimeter p = π r + d
Area A = π r² / 2
A half-round field or semicircle.
Pivot irrigation creates circular fields when the irrigation arm runs completely through the field. If there is an obstacle and the arm has to turn around, the resulting field is shaped like a sector of a circle. A semicircle is a specific type of such a sector. Other fractions of a circle cannot be created with this type of irrigation.
Semicircular fields are particularly common when, for crop rotation purposes, something different is grown on one half of the field than on the other, or when one half is left fallow. In this case, a different amount of water is needed for each half. Such fields, created by pivot irrigation and based on circles and their sectors, can be found in satellite images, for example, from Google Earth, in the USA and Egypt.
Semicircles are also found on many sports fields. The center circle of a soccer field, for example, is divided into two semicircles by the center line.
Last updated on 01/11/2026. Author: Jürgen Kummer
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