PLEN
Thematic maps: see the difference

Best map projection for thematic world maps

For a thematic world map, choose an equal-area projection, ideally Equal Earth. See how the visual weight of colour changes when a map enlarges some countries at the expense of others.

  • Greenland
  • Brazil

Equal Earth

Area preserved
Equal EarthTrue area proportions Greenland is highlighted in purple and Brazil in green.
True area proportionsRecommended

Mercator

Area distorted
MercatorHigh latitudes look larger Greenland is highlighted in purple and Brazil in green.
High latitudes look largerUnsuitable for this job

Each map is fitted to its own frame; they do not share an area scale. Compare country proportions within each map. Mercator omits the areas closest to the poles.

Brazil is larger. The map should show it.

An equal-area projection keeps that relationship honest. Mercator greatly enlarges Greenland, so its colour attracts too much attention.

Open the map: Equal EarthProjection guide
Other equal-area optionsGeometry: Natural Earth, public domain. Sources and methodology

Colour weighs as much as area

On a choropleth map each country is filled with one colour. Readers don't add up values; they take in patches of colour, so a large area feels more important. If the projection enlarges the north, data from Canada, Russia or Scandinavia gets an unfair advantage.

That is why thematic world maps use equal-area projections. Projection Wizard, which builds on John P. Snyder's guidelines, proposes equal-area or compromise projections for world maps and advises against conformal ones.

Equal Earth, Mollweide or Goode

Each of these keeps areas true. The choice depends on the shape of the map and on whether your data covers the seas too.

  • Equal Earth: the default choice, with readable continent shapes and straight parallels.
  • Mollweide: a classic for global data and sky maps, fitting the world into an ellipse.
  • Goode's interrupted homolosine: the truest land shapes, but the oceans are cut, so it suits land data only.

When an equal-area map is not enough

An equal-area map shows area honestly, but not the number of people. If a country's size should reflect its population, you need a cartogram, a map that deliberately resizes countries by the data.

A map of one continent or country needs a projection fitted to that area instead, such as a conic or an azimuthal one. Those are not in our map lab yet.

Frequently asked questions

An equal-area one, such as Equal Earth or Mollweide. Density is people per unit of area, so the map has to show areas in their true proportions. Otherwise the sparsely populated north looks more important than it is.

Robinson is a compromise, so it distorts area a little, most of all near the poles. It is usually fine for overview maps, but when the data is about area, an equal-area projection is the safer choice.

Each of its lobes has its own central meridian, and the cuts run through the oceans. The land is less distorted as a result, but marine data such as currents gets chopped up.

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MapEqual Earth mapDrag Greenland to the equator and see that it keeps its size.RankingMost densely populated countriesThe 25 countries with the highest population density.ArticleThe Equal Earth projectionA modern equal-area map with natural-looking continents.Which projectionProjection for comparing country sizesWhy comparisons need an equal-area map, and which one to pick.