Split a circle polygon in half in ArcGIS Pro and ArcMap

Summary

In some instances, it is necessary to split a circular area in half. The image below shows a circle with its attribute table before it is split in ArcGIS Pro. The total area is roughly 4400 square feet.

The image below shows a circle with its attribute table before it is split in ArcMap. The total area is roughly 8,631,337 square feet.

Procedure

Splitting a Circle in ArcGIS Pro

1. In the Contents Pane, select the layer in which the circle is located.
2. Click the Edit tab, and open the drop-down in the Tools group.

3. In the Divide section, click the Divide tool.

4. Select the circle to divide.
5. In the Divide tool, under Method, select Proportional Area.
6. Under Direction, select Choose a Polygon edge to set the direction.
7. Click an edge of the polygon to set the direction of the split

8. Under Values, set the Number of parts to 2.
9. Click Divide
   • This divides the circle into two equal halves

Note: 
If the circle looks distorted after splitting, undo the operation, ensure the coordinate system of the map and layer are the same, and try dividing the feature again.

Splitting a Circle in ArcMap

Note:
ArcMap has been retired as of March 1, 2026. There are no plans for future releases of ArcMap, and it is recommended that you migrate to ArcGIS Pro. See Migrate from ArcMap to ArcGIS Pro for more information.

To split a circle into half using Cut Polygons Tool, follow the steps below:

1. In ArcMap, start an edit session. Select the circle 'polygon' to split.

Note:
If the Editor toolbar does not appear, click Customize > Toolbars > Editor.

2. In the Editor toolbar, click the Cut Polygons Tool icon . The Straight Segment icon is automatically selected .
3. Click Editor > Options. In the Editing Options window, enable the Show feature construction toolbar option, and click OK.

4. Click anywhere at the edge of the circle. The Feature Construction toolbar appears.

Note:
To ease line construction, enable snapping options by clicking Editor > Snapping > Snapping Toolbar.

5. In the Feature Construction toolbar, click the Constrain Perpendicular icon . Creating a straight line that is perpendicular to any edge of a circle draws across the centroid to split the circle in half. For more information on creating a line at an angle, refer to ArcMap: Creating a segment using an angle and a length.
6. Draw a straight line across the circle and snap the line at the other edge of the circle. The circle automatically splits. Opening the attribute table shows the circle is split into two. In this example, each half has an area of roughly 4,315,668 square feet.