The Mercator projection, and why it makes Greenland look huge

What the Mercator projection is

A map projection is a way of drawing the round Earth on a flat surface. In 1569, the Flemish mapmaker Gerardus Mercator published a world map designed for sailors. Its Latin title, Nova et aucta orbis terrae descriptio ad usum navigantium emendate accommodata, means “a new and more complete representation of the terrestrial globe, properly adapted for use in navigation.”

Its great advantage was that any course with a constant compass bearing, called a rhumb line, is a straight line on the map. A navigator could draw a straight line from one port to another, measure its angle, and steer by that bearing the whole way.

How it works

On a globe, the lines of longitude that run from pole to pole get closer together as they near the poles. Mercator draws them as straight, parallel lines instead. So the farther a place is from the equator, the more the map stretches it from east to west. At 60° latitude, the lines of longitude are really half as far apart as at the equator, so the map stretches that part of the world to twice its width.

If Mercator had stopped there, everything far from the equator would have looked squashed. So he also stretched the map from north to south by roughly the same amount. The English mathematician Edward Wright published the exact spacing in 1599. Stretching north to south as much as east to west keeps angles and the shapes of small areas correct. Mapmakers call a projection like this conformal.

The cost is size. Each place is stretched in both directions, so its area grows by the square of the stretch: stretch a place to twice its width and twice its height, and it covers four times the area.

Latitude	For example	Distances stretched	Areas inflated
0°	Quito, Ecuador	1×	1×
30°	Cairo, Egypt	1.15×	1.33×
45°	Minneapolis, United States	1.41×	2×
60°	Oslo, Norway	2×	4×
70°	Tromsø, Norway	2.9×	8.5×
80°	Northern Greenland	5.8×	33×
90°	The North and South Poles	Without limit	Without limit

For the mathematically curious: at latitude φ, Mercator stretches distances by 1 / cos φ and areas by 1 / cos² φ.

This is why Greenland, which lies between about 60° and 83° north, looks enormous. Mercator draws it about 16 times too big, while Africa, across the equator, is drawn close to its true size.

Why the poles are missing

The stretching grows without limit as you get closer to the poles, so a Mercator map can never show them. Every Mercator map stops somewhere. Web maps stop at about 85° north and south. That makes the whole world a perfect square, which is easy to divide into the small square images, or tiles, that web maps are built from.

Why Mercator is still so common

• Navigation. Most nautical charts still use Mercator, for the same reason Mercator made it: courses with a constant bearing are straight lines.
• Web maps. When Google Maps launched in 2005, it used a version of Mercator now called Web Mercator. OpenStreetMap, Bing Maps and most online maps use it too. Because it is very nearly conformal, streets meet at the right angles at every zoom level, and north is straight up everywhere on the map.
• Habit. Generations of people learned geography from Mercator wall maps, so its shapes are the ones that look right.

Why it is the wrong map for comparing sizes

In 1827, the mathematician Carl Friedrich Gauss proved that a round surface cannot be flattened without distortion. One result is that no flat map can keep both angles and areas true at the same time. Mercator keeps angles. To compare the sizes of countries, you need a map that keeps areas instead, called an equal-area projection.

Alternatives to the Mercator projection

Projection	Year	Keeps true	Trade-off
Mercator	1569	Angles and the shapes of small areas	Sizes grow toward the poles, which cannot be shown
Gall–⁠Peters	1855	Areas	Continents near the equator look tall and thin
Winkel tripel	1921	Neither; a compromise	Low overall distortion; adopted by National Geographic for its world maps in 1998
Robinson	1963	Neither; a compromise	Some distortion of both size and shape
Equal Earth	2018	Areas	Some shape distortion near the edges; encouraged by the United Nations in 2026

Who made them: Mercator by Gerardus Mercator; Gall–⁠Peters by James Gall, promoted by Arno Peters from 1973; Winkel tripel by Oswald Winkel; Robinson by Arthur H. Robinson; Equal Earth by Bojan Šavrič, Tom Patterson and Bernhard Jenny.

Mercator and the 2026 UN vote

On September 4, 2026, the UN General Assembly voted 164 to 1 to encourage the use of Equal Earth and other equal-area maps when the sizes of continents matter. The resolution leaves maps used for navigation as they are. Read what the UN decided and why, or see more comparisons like Greenland and Africa in the true size of countries.

See it for yourself

TrueWorld Maps is built on a Mercator map, so you can see the distortion for yourself. Drag a country toward a pole and it swells; drag it to the equator and it shrinks to its true size.

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Sources

1. Map Projections: A Working Manual, John P. Snyder, U.S. Geological Survey Professional Paper 1395, 1987. The Mercator and other projections, with their formulas and history.
2. Nautical charts: Nautical cartography, Office of Coast Survey, National Oceanic and Atmospheric Administration.
3. History and dates, from Wikipedia: Mercator 1569 world map (including the translated title), Web Mercator projection, Gall–Peters projection, Winkel tripel projection, Robinson projection and Theorema Egregium.
4. Web Mercator definition (EPSG code 3857, WGS 84 / Pseudo-Mercator), used by online maps.
5. The Equal Earth map projection, B. Šavrič, T. Patterson and B. Jenny, International Journal of Geographical Information Science, 2019.
6. General Assembly adopts text to “Correct the Map,” among others…, UN Meetings Coverage and Press Releases, September 4, 2026.
7. Map outlines: Natural Earth countries at 1:50 million scale, public domain.