How do I make a population density map?

Load region boundaries, attach population, get a land area per region, then derive density as population divided by area and map that rate. In [Groundtruth](/tools/map) you can compute area geodesically and create the density variable with a formula, all in the browser.

Should I map population or population density?

Map density (people per square kilometre) to show where people concentrate. A raw population map mostly shows which regions are large or populous, hiding the actual pattern.

What classification is best for density?

Density is strongly skewed, so natural breaks (Jenks) or quantile usually work best. Equal interval tends to collapse most regions into the lowest class. A log transform can also help.

Where do I get land area for each region?

Many boundary datasets include an area field. If yours does not, a tool that computes real geodesic area from the geometry can produce square kilometres for each region.

Spatial data

How to Make a Population Density Map

A population map that shades regions by total population mostly shows which regions are big. A population density map, people per unit of area, shows where people actually concentrate, which is almost always the question you meant to ask. This guide explains the difference, the arithmetic, and the classification, and walks through building one in the browser with Groundtruth.

7 min read · Updated August 24, 2026

Density, not count

Population is a count: how many people live in a region. Density is a rate: people divided by land area, usually per square kilometre. On a choropleth, always map the rate. A count map is dominated by the largest and most populous units and hides the pattern of concentration. A density map reveals the crowded core and the empty periphery that the count conceals.

The arithmetic

Density = population / land area. Use land area, not total area, if you can, so large lakes or sea do not dilute the figure. If your data is in people and square kilometres, density is people per km squared directly.

What you need

Boundaries of your regions as a shapefile or GeoJSON (Natural Earth, geoBoundaries, GADM, or your statistics office).
A population figure per region, from a census or official estimate.
A land area per region. Many boundary datasets include it; if not, a tool that computes real geodesic area can supply it.

Step by step

Step 1Load boundaries

Drag your shapefile or GeoJSON onto Groundtruth. It reads the file locally and detects the coordinate system.

Step 2Get population in

If population is in a spreadsheet, join it on region name or code with Join a spreadsheet (CSV).

Step 3Get area

If your data has an area column, use it. If not, the tool computes real area in square kilometres from the geometry, geodesically for longitude and latitude data.

Step 4Compute density

Use New variable from a formula and enter population divided by area. The tool computes it for every region as a new mappable variable.

Step 5Classify and map

Density is highly skewed (a few dense cities, many sparse rural areas), so natural breaks (Jenks) usually reads best. Compare it against quantile to be sure.

Step 6Export

Draft a caption and export the map as SVG or PNG, or save the project so the density calculation is reproducible.

Reading a density map honestly

Density is extremely skewed, so equal-interval classes usually collapse almost everything into the lowest class. Prefer Jenks or quantile.
The modifiable areal unit problem is real: the same population looks denser or sparser depending on how the regions are drawn. State your units.
A single dense city can dominate the colour scale. If it does, say so, or map on a log scale by deriving log density with a formula.

For the general mapping choices behind this, see how to make a choropleth map and choropleth classification methods.

Frequently asked questions

How do I make a population density map?: Load region boundaries, attach population, get a land area per region, then derive density as population divided by area and map that rate. In Groundtruth you can compute area geodesically and create the density variable with a formula, all in the browser.
Should I map population or population density?: Map density (people per square kilometre) to show where people concentrate. A raw population map mostly shows which regions are large or populous, hiding the actual pattern.
What classification is best for density?: Density is strongly skewed, so natural breaks (Jenks) or quantile usually work best. Equal interval tends to collapse most regions into the lowest class. A log transform can also help.
Where do I get land area for each region?: Many boundary datasets include an area field. If yours does not, a tool that computes real geodesic area from the geometry can produce square kilometres for each region.

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