How polygon merging works
A merge—often called a dissolve or union—combines the occupied area of selected polygons. Shared internal boundaries are removed where the geometries overlap or touch.
- Import or draw the polygons. Open your source file and confirm that the intended features are visible.
- Select the inputs. Pick the polygons you want to combine. Avoid including unrelated features.
- Run Merge. Preview the result and check whether it becomes a Polygon or MultiPolygon.
- Review attributes. Decide which feature name and properties should belong to the merged result.
- Validate and export. Check the output geometry before downloading it.
Polygon versus MultiPolygon output
If the selected areas overlap or touch in a way that creates one continuous area, the result can be a Polygon. If separate islands remain, the geometrically correct result is normally a MultiPolygon.
Merging geometry does not automatically reconcile data. When input features have different names, IDs or classifications, you must decide which properties the new feature should retain.
Typical uses
- Combining adjacent service areas into one operating region.
- Dissolving parcel-like polygons into a broader planning boundary.
- Combining several drawn sections before exporting a final site outline.
- Removing internal boundaries from overlapping coverage polygons.
When merge results look wrong
Validate the source features first. Self-intersections, tiny gaps, duplicate boundaries and unexpectedly different coordinate systems can produce surprising unions. Zoom closely around shared edges and compare the output area with the inputs.
Ready to work on your file?
Open the editor, import your geometry and use the relevant operation from the toolbar or More menu.
Open the editor