KMZ to CSV Converter: Shared Maps into a Spreadsheet

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Features in this file

NameTypeFolderVerticesLengthArea

A four step pipeline. First a KMZ arrives, holding placemarks and often icons and overlays. Second it is unzipped and read in the browser, with icons and overlays left behind because they have no tabular form. Third every placemark becomes a row carrying name, folder, vertex count, length, area and a representative coordinate, plus the columns the sender attached. Fourth the result opens in Excel for sorting, filtering, totalling and pivoting. A band explains that a map will not total the access track at 91.172 km, count how many holes each contractor drilled, or say which sites are missing a depth.
The last row is the point of the exercise. Everything a map is bad at answering is a sort or a total once the data is a table.

How to use this tool

Drop a .kmz file above. It is unzipped in your browser, the KML inside is read, and every placemark becomes a row. Press Convert to CSV and open the result in Excel.

If you have a plain .kml, use the KML to CSV Converter. It skips the unzip step and is otherwise the same.

What a spreadsheet lets you ask that a map cannot

A map is very good at showing you where things are and very bad at telling you how many, how much and which. Those are table questions.

Once a shared map is a spreadsheet you can sort by depth to find the deepest hole, filter to one contractor, total the access tracks, count how many sites are missing a value, or pivot by folder to see how the work was split. None of that is available while the data is still a map, and all of it is thirty seconds of work in a spreadsheet.

That is the reason this conversion exists. It is not about the format, it is about being able to add things up.

What comes out of the archive, and what does not

A KMZ is a zip. Inside there is normally a doc.kml holding the placemarks, and often a files folder with icon images, ground overlays and legend graphics.

Only the KML becomes rows. Icons, overlays and legends have no tabular form at all, so they are left behind. If the sender used different icons to distinguish two kinds of site, that distinction is not in the table and you will need to reconstruct it from the names or the folders.

This is worth checking before you rely on the output. Open the KMZ in Google Earth first, look at whether the meaning is carried by the icons or by the data, and if it is the icons, ask the sender for a version with the classification in a field.

A worked check you can repeat on paper

Confirm nothing was dropped, without any tools beyond a text editor.

Take a copy of the KMZ and rename the extension to .zip, then extract it. Open the doc.kml and search for the word Placemark. Every placemark produces one opening tag, so the number of occurrences of the opening tag is the number of features you should expect.

  • Count the opening Placemark tags in the KML.
  • Convert the file here and count the data rows in the CSV, which is the total line count minus one for the header.
  • The two numbers should be identical.

If the CSV has fewer rows, something was lost, and the usual casualty is a MultiGeometry. That is a placemark holding several parts at once, and a naive parser reads only the first part and discards the rest. This engine reads all of them, and there is a permanent test asserting it, because an early version did exactly that and lost a two segment track.

It is worth doing this check once against a file you know, so that you trust the output afterwards.

Mistakes that catch people out

Renaming the .kmz to .csv and hoping. A KMZ is compressed binary. Excel will open it and show you nothing useful.

Expecting the shapes. Lines and polygons become a row with a representative coordinate, a vertex count and a measurement. The boundary itself is not in the table and cannot be recovered from it.

Losing the folder structure by ignoring the column. A shared map is often organised by phase or by team, and the folder path is the only place that survives.

Assuming every placemark carries the same fields. Different senders attach different ExtendedData to different features, so a column may be populated for some rows and empty for others. That is the data, not a fault in the conversion.

Trusting a converter that never complains. If you feed it a file and get a table with no warnings and fewer rows than you expected, check the count by hand using the method above.

Related Calculators and Reference

A shared map becoming a table is normally the start of an analysis job.