Create a population choropleth map with QGIS in 15 minutes

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Quickly obtaining a visual representation of population distribution is a decisive asset for any geospatial project. This tutorial guides you step by step in QGIS to produce, in just 15 minutes, a clear and professional choropleth map.

Why Choose QGIS for a Choropleth Map

In terms of GIS, QGIS stands out for its free cost and strong community. It natively integrates advanced symbology tools, making it ideal for mapping demographic data. Thanks to numerous modules, you can adjust your styles without coding, while easily importing your own datasets.

Free software rich in features

QGIS offers an exhaustive range of features: SQL queries, geoprocessing, dedicated plugins… Not to mention the ability to import GeoJSON, SHP, or CSV files for your population statistics. This user-friendliness avoids multiplying software and centralizes cartographic production in a single environment.

Adapted to demographic data

Whether you have census data by municipality, neighborhood, or surveys down to IRIS level, QGIS handles all levels of granularity. It facilitates data aggregation, creation of joins between attribute tables, and formatting of population ranges.

Prepare Your Project in a Few Clicks

Import base maps and data

Start by loading a base map (Shapefile or GeoPackage). Then add your demographic data table (CSV or GeoJSON), ensuring it contains a geographic identifier (INSEE code, for example). QGIS automatically links the two sources as soon as a common column is detected.

Check data quality

Before any classification, open the attribute table and inspect missing values, duplicates, or statistical anomalies. A step often overlooked but crucial to avoid empty or erroneous ranges disrupting the final map.

Create the Choropleth Map in 6 Steps

1. Load the layers

In the “Layers” panel, check that your base map and table are both activated. The easiest way is drag-and-drop to avoid selecting the wrong file.

2. Set up the choropleth symbology

Right-click on the geographic layer and choose « Properties → Symbology ». Select the « Graduated » mode and choose the population field. You will see a gradient ready to be adjusted appear.

3. Choose the classification method

• Quantiles for classes equal in number of geographic units.
• Jenks to emphasize natural breaks in the data.
• Equal interval if you want a uniform approach.

4. Refine the legend

Rename each class to clearly indicate the value range, for example « 0–50 inh/km² ». Modify the rounding and add a prefix if necessary (inhabitants or percentage).

5. Add labels and map elements

Include a scale, a North arrow, and dynamic labels for the main areas. In the « Composer » tab, you can fine-tune the final layout.

6. Export as image or PDF

In the export window, select the resolution (300 DPI for printing). Choose a vector format (PDF, SVG) if you want to keep the flexibility of later editing.

Tips for impactful rendering

• Favor a perceptual palette adapted for colorblind people (e.g., Viridis).
• Ensure sufficient contrast between classes for quick reading.
• Limit the number of ranges to 5–7 to avoid cognitive overload.
• Add annotations to contextualize high-density areas.

Example distribution table

Enhance your analysis

By crossing population density with socio-economic or environmental indicators, you will obtain a more nuanced view of territorial dynamics and be able to guide decision-making in an informed manner.

FAQ