What is the Mercator projection?
The Mercator projection is a 1569 navigation map: it keeps every compass bearing a straight line, but to do that it stretches land larger the further it sits from the equator — which is why Greenland looks the size of Africa.
By W. Viljoen · Published 21 June 2026
Greenland- Greenland2,142,677 km² · 9.9× on the map
Both panels are drawn to the same scale. On the left, each country is the size the Mercator map gives it; on the right, its true size with the latitude distortion removed.A map built for sailors
The Mercator projection was created by the Flemish cartographer Gerardus
Mercator in 1569, and it was built to solve one problem: navigation. On his
map, a course of constant compass bearing — say, "hold south-west" — is a
perfectly straight line. A sailor could lay a ruler between two ports, read off
the angle, and steer it without recalculating. No other common map does this,
which is why Mercator became the standard sea chart for centuries.
The trade-off: size
That straight-line magic isn't free. To keep every direction true, Mercator
stretches the map east–west as you move away from the equator — and then stretches
it north–south by the same amount, so shapes don't skew. Stretch both directions
and you inflate area, by a factor of sec²(latitude):
- On the equator: no distortion at all (1×).
- At 45°: everything is drawn twice its true size.
- At 60°: four times.
- Toward the poles: the inflation runs to infinity, which is why the map is
cropped near 85°.
So the further a country sits from the equator, the bigger the map draws it.
Greenland, up in the Arctic, is inflated about ninefold — which is why it looks as
large as Africa, even though Africa is really about 14 times its size.
Why the world still uses it
If it distorts size so badly, why is it everywhere? Two reasons. It's
conformal — it preserves local shapes and angles, so coastlines and street
grids look right close up. And it tiles neatly into squares with north always up,
which is exactly what digital maps need: Google Maps, Bing and most of the web run
on a version called "Web Mercator." The projection built for ocean navigation
turned out to be ideal for zooming and panning a screen.
See it for yourself
The highlighted country is Greenland — drag it down toward the equator and
watch its true size emerge as the inflation drains away. Then explore the
comparisons to see how the same rule reshapes the rest of the world.