True Size
Maps lie about size. Drag a country and see.
Greenland covers 2,166,086 square kilometers. Africa covers 30,315,078 square kilometers across 55 countries, about 14 times more, yet a Mercator map draws the two at nearly the same size. The reason is that Mercator stretches everything away from the equator by 1/cos(latitude). Greenland's centre sits near 72 degrees north, where that factor is about 3.2, so it is drawn roughly 3.2 times too wide and around 10 times too large in area. Africa straddles the equator, where Mercator introduces no distortion at all, which is why it is the country nobody suspects of being drawn too small.
Greenland
True area: 2,166,086 km2
Mercator inflates it 3.24x at its latitude
Brazil
True area: 8,515,767 km2
Mercator inflates it 1.02x at its latitude
Mercator view draws each country the way a web map does: inflated by 1/cos(latitude) at its own latitude, which is why Greenland can look bigger than Brazil. True size gives both outlines the same kilometers per pixel, so their drawn sizes compare honestly. Shapes keep their Mercator-projected outlines in both views.
Areas and coordinates: mledoze/countries (ODbL). Outlines: Natural Earth via world-atlas (public domain).
About this visualization
About this data
Mercator maps stretch everything away from the equator by 1/cos(latitude): at 60 degrees north a country is drawn twice as wide as it would be at the equator, and Greenland (real area 2,166,086 km2) ends up looking like Africa. Here you can flip between Mercator view (each country inflated at its own latitude, exactly as web maps draw it) and true size (both outlines at the same kilometers per pixel), to see how much the projection lies.
Common questions
- Why does Greenland look as big as Africa on a map?
- Because the Mercator projection stretches everything away from the equator by a factor of 1 divided by the cosine of the latitude. Greenland sits far north, so it is inflated enormously. Its real area is 2,166,086 square kilometers against Africa's 30,315,078, so Africa is about 14 times larger despite the two appearing similar on the map.
- How much does the Mercator projection distort?
- At 60 degrees latitude a country is drawn about twice as wide as it would be at the equator, and the effect accelerates toward the poles. At the equator there is no distortion at all, which is why equatorial countries look deceptively small next to northern ones.
- Why do maps still use Mercator if it distorts so badly?
- Because Mercator preserves angles, which makes it excellent for navigation: a straight line on the map is a constant compass bearing. That property is why it was devised in 1569, and why web maps still use it, since it also stays consistent as you zoom.