What is a map projection?
A map projection is a set of rules for turning the curved surface of the Earth into a flat map. You cannot flatten a sphere without stretching or tearing it, so every flat world map distorts something: the size of areas, the shape of countries, distances, or directions. Choosing a projection means choosing which of these to keep and which to give up.
How to use this page
- Pick a projection on the left to redraw the world in it. The card below explains what it preserves and where it fails.
- Drag the map to rotate the Earth. On flat maps this moves the central meridian; on the globe and polar views you can turn the world in any direction.
- Turn on Distortion circles. Each red circle covers the same area on the real globe, so you can see at a glance where a projection swells, squashes or shears the land.
The four things a projection can keep
- Area (equal-area): every region has its true relative size. Examples: Equal Earth, Mollweide. Best for maps of population, land use or anything you compare by size.
- Shape and angles (conformal): small shapes and the angles between roads and coastlines stay true. Examples: Mercator, Stereographic. Used for navigation and web street maps.
- Distance (equidistant): distances are true along certain lines or from one point. Examples: Equirectangular along meridians, Azimuthal equidistant from the center.
- Direction (azimuthal): directions from the center point are true. Examples: Azimuthal equidistant, Orthographic.
No projection can be both equal-area and conformal. Compromise projections such as Robinson and Winkel Tripel keep none of the four exactly, but spread the errors so the whole world looks reasonable.
Which projection should I use?
| Purpose | Good choice |
|---|---|
| General world map for a wall or a report | Winkel Tripel, Robinson, Equal Earth |
| Comparing countries by size, thematic data | Equal Earth, Mollweide |
| Street maps and navigation | Mercator (Web Mercator) |
| Arctic or Antarctic maps | Stereographic, Azimuthal equidistant |
| Distances from one city, flight ranges | Azimuthal equidistant centered on that city |
| Satellite data, 3D globe textures | Equirectangular |
| Showing a region in its global setting | Orthographic |
Why does Greenland look so big?
Most online maps use Web Mercator. To keep shapes true, Mercator stretches everything more and more toward the poles: at 60° latitude areas are drawn four times too large, and at 80° more than thirty times. Greenland looks about as large as Africa, but Africa is roughly 14 times bigger. Switch to Equal Earth above and the two take their real proportions.
Frequently asked questions
What is the most accurate map projection?
No flat map is accurate in every way. Equal-area projections such as Equal Earth show true sizes, conformal projections such as Mercator show true local shapes, and compromise projections such as Winkel Tripel keep the overall distortion lowest. Only a globe is accurate in every respect.
What projection does Google Maps use?
Google Maps, Mapbox and most web maps use Web Mercator, a version of the Mercator projection. When you zoom out far enough, some web maps switch to a 3D globe view instead.
Is the Mercator projection wrong?
It is not wrong, but it was designed for navigation, not for comparing sizes. It keeps angles and local shapes true while greatly enlarging areas near the poles, so it is a poor choice for a general world map.
What projection does National Geographic use?
National Geographic has used the Winkel Tripel projection for its world maps since 1998. Before that it used the Robinson projection.
What is the Tissot indicatrix?
It is a set of small circles of identical size placed on the globe and then drawn with a projection. How the circles change size and shape shows exactly how and where the projection distorts.
Which projection is best for a world map?
For a general world map, Winkel Tripel, Robinson or Equal Earth are common choices. Use an equal-area projection like Equal Earth whenever the map compares quantities by area.