Choropleth Map Maker: Create a Thematic Map from Excel

A thematic map from your spreadsheet

A thematic map shows how a topic such as population density, sales, applications or a rate is distributed across space. On a choropleth map, the most common kind, each administrative unit is filled with the color of the class its value falls into. This tool joins an Excel or CSV table to boundaries and turns it into a map ready for a report or a web page within minutes. Province and district boundaries of Türkiye are built in; for any other country, region or your own service areas you can load a GeoJSON, Shapefile or KML boundary file.

How to use it

1. Choose the boundary layer: Türkiye provinces, Türkiye districts or your own file.
2. Copy the table from Excel and paste it, or choose an .xlsx, .xls or .csv file. The first row must contain the column headers.
3. The tool picks the key column and the value column automatically. The matching report shows the match rate and the rows that did not match; you can fix them by choosing the right boundary from the suggestions or the full list.
4. Choose the classification method, the number of classes and the palette, then write the title, subtitle, source note and legend title.
5. Download the map as PNG, SVG or embeddable HTML, and the joined data as GeoJSON, Shapefile or CSV.

Name matching

The same region is often written in different ways across spreadsheets. Before comparing, the tool converts names to lower case, removes accents, spaces and punctuation, and drops words such as "Province", "District" or "Region". Numeric codes match regardless of leading zeros. For the remaining rows it suggests candidates ranked by Jaro-Winkler similarity; only a clear best candidate is accepted automatically, and those rows are listed separately so you can check them. When several districts share the same name, add the province column as a second key.

Classification methods

• Quantile: Each class contains about the same number of units. Good for ranking; very close values can end up in different classes.
• Natural breaks (Jenks): Finds the breaks that minimize the variance within classes and reveals clusters in the data.
• Equal interval: Splits the range between the minimum and the maximum into equal parts; outliers can push most units into one class.
• Manual breaks: You set the breaks yourself, for example to compare years or follow official thresholds.
• Categorical: Text values such as region, party or status are colored with a qualitative palette.

The value distribution chart draws the class breaks on a histogram, so you can see how many units fall into each class as you change the method.

Totals or rates

Totals such as population or total sales are usually misleading on a choropleth map because large or populous units come out high anyway. For comparison, divide the value by area to show density (per km²) or by another column to show a rate (per 100, 1,000 or 100,000). Area is computed from the true size of each boundary on the WGS84 ellipsoid. The default projection is Albers equal-area, which keeps the size of each unit on the map proportional to its real area.

Data and method

The Türkiye province and district boundaries are derived from OpenStreetMap data (© OpenStreetMap contributors, ODbL 1.0); a source line is added automatically to maps that use them. The same boundaries can be downloaded as Shapefile, GeoJSON, KML and DXF from the Turkey administrative boundaries page. Color palettes come from Cynthia Brewer's ColorBrewer (Apache 2.0) and the viridis family. Projections are computed with proj4js 2.9.0 (MIT), ellipsoidal area with GeographicLib geodesic 2.1.1 (MIT), Excel files are read with SheetJS xlsx 0.18.5 (Apache 2.0), CSV with PapaParse 5.4.1 (MIT), shapefiles with shpjs 6.1.0 (MIT) and JSZip 3.10.1 (MIT), and KML with @tmcw/togeojson 5.8.0 (BSD-2-Clause). Matching, classification, SVG rendering and the shapefile writer are this page's own code.

Accuracy limits

• The built-in boundaries are simplified for general map scales and should not replace official administrative or cadastral data.
• When administrative divisions change, some rows in older tables may not match; always check the matching report.
• Similarity suggestions are an aid; they can be wrong for short or similar names.

Rodosto Teknoloji builds dashboards and web mapping solutions that keep such data up to date for organizations. You can learn more on the Rodosto Teknoloji website or reach us through the contact page.