What Is the Equal Earth Projection?

The Equal Earth projection is a pseudocylindrical, equal-area projection designed for world maps. It keeps the relative area of countries and continents correct while presenting the world as one continuous, rounded map. Bojan Šavrič, Tom Patterson and Bernhard Jenny designed it in 2018 as an equal-area alternative with some of the visual familiarity of the Robinson projection.

Equal Earth is a particularly strong choice when a world map asks readers to compare how much of the Earth's surface different regions occupy. It does not preserve every shape, distance or direction, and it is not intended to replace every projection.

What Equal Earth preserves

Equal area has a precise meaning: the ratio between an area on the map and the corresponding area on the Earth is constant. If one region covers twice the surface area of another, it also occupies twice the mapped area.

The important word is relative. Equal Earth is not promising that a square centimetre on a printed map has one universal ground-area meaning independent of map scale. It is promising that area ratios remain correct: a region of 2 million square kilometres occupies twice the mapped area of a region of 1 million square kilometres, whether the two regions are near the equator or at high latitude.

This matters whenever polygon size affects interpretation. On a world map of forests, agricultural land, protected areas or total emissions, readers do not respond only to colour and labels. They also see how much space each region takes up. A projection that greatly enlarges high latitudes can give those regions more visual weight than their physical area warrants.

Equal Earth's promise is limited to area. To keep area proportional on a flat map, it must alter local shape and scale. Continental outlines stretch increasingly towards the outer meridians and high latitudes. A route drawn between two cities is not guaranteed to have the correct distance or bearing, and the projection is not suitable for navigation or precise local engineering.

Why it resembles a familiar world map

Equal-area projections existed long before Equal Earth. Mollweide, Eckert IV and interrupted forms of the Goode Homolosine projection are established options. The contribution of Equal Earth was not the invention of equal-area mapping; it was a deliberate combination of area preservation with a continuous outline designed to be visually approachable.

Its parallels are straight, its meridians curve away from the central meridian, and its poles appear as lines rather than points. The outer boundary is rounded rather than rectangular. The result resembles the overall rhythm of Robinson while making a mathematical commitment Robinson does not: Equal Earth preserves relative area exactly.

That familiarity is useful, but it should not become the only selection criterion. A map centred on Greenwich cuts the Pacific at its outer edges. A Pacific-centred version moves the least-distorted central region and changes what is split. Projection, central meridian and map extent are three connected editorial choices.

When Equal Earth is a good choice

Equal Earth is well suited to:

global choropleths and other thematic world maps;
comparisons involving land area or the spatial footprint of a phenomenon;
classroom and institutional maps where continent size should remain proportional;
global editorial graphics that need a continuous world rather than interrupted lobes;
overview maps whose rendering system is not restricted to a Web Mercator tile grid.

It can also be a useful neutral-looking base for a global map in which the theme is not explicitly area-based. “Neutral” here means that it does not systematically inflate the mapped area of high-latitude regions; it does not mean that the map is free of design or political choices.

Equal Earth is usually not the first choice for a country-scale engineering project, a nautical chart, a polar study or an application that must consume standard Web Mercator tiles. A regional equal-area projection can often distribute distortion more effectively over a continent or country than a global projection can.

Equal Earth compared with Web Mercator

The contrast is clearest at high latitudes, where Web Mercator keeps local angles but increases scale rapidly away from the equator. At 60° latitude, the spherical Mercator scale factor is about two in each direction, so mapped area is inflated by roughly a factor of four; Equal Earth instead keeps area proportional and allows the shapes of the distortion ellipses to change.

That makes Equal Earth the more defensible display for a world-scale area comparison, but it does not make Web Mercator obsolete: its square, recursively divisible coordinate space underpins a large web-tile ecosystem. A product can therefore reasonably use Equal Earth for a world overview and Web Mercator after the reader moves into local exploration.

Implementation and CRS identifiers

Equal Earth is available in major geospatial software through libraries such as PROJ. The projection method is commonly expressed as +proj=eqearth. EPSG:8857 identifies the WGS 84 / Equal Earth Greenwich projected CRS; other Equal Earth CRS definitions can use different central meridians or reference frames.

This is more than a distinction in nomenclature. “Equal Earth” names a projection method, whereas an EPSG CRS definition also supplies the datum, coordinate system, units and parameters needed to interpret coordinates. If an exported layer is intended for reuse, store the complete CRS definition rather than only the method name.

What the projection cannot decide

Using an equal-area projection does not validate the data drawn on it. It cannot determine which boundaries are legitimate, whether missing values are shown honestly, whether a classification hides variation or whether a dataset is current enough for the claim.

Nor does area preservation settle how the world should be centred. A map of Pacific island states may be poorly served by a Greenwich-centred layout even if its area property is correct. Antarctica can dominate the lower margin of an equal-area map unless the extent and visual hierarchy are handled deliberately.

The best reason to choose Equal Earth is therefore specific: the map covers the world, relative area matters, continuity is valuable and the remaining shape distortion is acceptable. That is a strong case, but it is not a universal one.

References

The Equal Earth map projection. The peer-reviewed paper by Bojan Šavrič, Tom Patterson and Bernhard Jenny.
PROJ: Equal Earth. Technical implementation and parameters.
EPSG Geodetic Parameter Dataset. Authoritative registry containing the WGS 84 / Equal Earth Greenwich CRS definition.