Greenland Isn't Really the Size of Africa: The Map That Stretches the Poles

On the world map most of us grew up with, Greenland looks about as big as Africa. In reality Africa is fourteen times larger. The map isn't careless. It was built to keep sailors' compass bearings straight, and the price of that promise is that the world swells the closer you get to the poles.

Picture the world map that hangs on classroom walls. Up at the top, there's Greenland, a great white slab. Down the middle sits Africa. And they look, more or less, the same size.

They aren't. Not remotely. In reality, Africa's area is fourteen times as large as Greenland's.

That's not a small rounding error. That's the kind of mistake you'd expect someone to notice. And people did notice. The map was drawn that way on purpose.

You can't flatten a ball

To see why, start with a simpler problem. Take an orange, peel it, and try to lay the peel flat on the table without tearing it or squashing it.

You can't. It splits. Or it bunches up. Or both.

The same is true of the Earth. Mathematicians proved long ago that a sphere can't be flattened onto a plane without distortion. Which means every flat map of the world distorts the surface in some way. There is no perfect map. There are only different choices about what to get wrong.

Mercator's choice

The map we're picturing is a version of one presented in 1569 by the Flemish geographer and mapmaker Gerardus Mercator.

Here's the mechanism, in plain terms. On a globe, the lines of longitude, the ones running from pole to pole, squeeze closer together as they head north or south, until they meet at the poles. On Mercator's map, they don't. They're drawn as straight, parallel lines, evenly spaced all the way up.

So the further you get from the equator, the more the map has to stretch things sideways to keep those lines apart. At 60 degrees north, the stretch is already a factor of two.

But Mercator didn't stop there. If he'd only stretched the map sideways, every shape near the poles would look squashed and fat. So at each latitude, he stretched it north to south by the same amount.

That's the clever bit. Stretch something by the same amount in both directions and, in any small patch, the shape stays right. Angles stay right. A small island near the pole is the right shape. It's just enormous.

Mapmakers call this property conformal: the map preserves angles locally. There's a neat way to see it. Imagine drawing identical little circles all over a globe and then projecting them onto the map. On Mercator's map, they stay circles. They just get bigger and bigger as you head away from the equator.

The distortion was the point

Here's the counterintuitive bit. That swelling wasn't a flaw Mercator couldn't fix. It was the price of the feature he actually wanted.

On a Mercator map, any course of constant compass bearing shows up as a straight line.

For a sailor, that's enormously useful. If you want to get from one port to another, you draw a straight line between them on the chart, measure its angle, and steer that compass bearing. Keep the needle on that heading and you'll follow the line.

Mercator's map was built to answer one question: which way should I steer? It answers that question beautifully. It just wasn't built to tell you how big anything is.

The poles that never appear

Push the stretching all the way, and something odd happens. The scale keeps growing as you approach the poles, until at the poles themselves it becomes infinite.

So a Mercator map can never fully show the polar regions. The top and bottom are simply cut off somewhere. Antarctica, sitting at the bottom of the world where all the lines of longitude meet, would appear infinitely large.

And yet the design is still everywhere. Many major online mapping services, including Google Maps, use a variant of Mercator's projection. The reason is the same property that suited sailors. Because the projection keeps shapes right in any small patch, when you zoom in on a street, the corners are the right angles and the streets are the right shape. For finding your way across a city, that's exactly what you want. It's only when you zoom all the way out that Greenland starts to look like a continent.

If you want to see the effect for yourself, there are interactive sites that let you drag countries around the map and watch them shrink or swell as they move between the equator and the poles. Slide Greenland down onto Africa and the truth becomes very obvious, very quickly.

Every map tells a lie

So is the answer simply to use a different map? Partly. But every alternative makes its own trade.

Each projection keeps some properties and sacrifices others. The main ones are shape, area, distance and direction, and no projection can be best at everything. In particular, a map can't be both conformal, keeping shapes right locally, and equal-area, keeping sizes right.

Equal-area maps do exactly what Mercator's doesn't. They show the true relative sizes of countries and continents. But to do it, they distort shapes instead. Draw those same little circles on an equal-area map and they all come out the same area, but many of them are no longer circles.

Mercator's map has had its critics, who argue that it's poorly suited to showing the whole world, precisely because of the unbalanced way it represents landmasses. That's fair, if you're using it to compare sizes. It's less fair if you're using it to steer a ship.

A map is an answer to a question

Which is really the lesson. A map isn't a photograph of the world. It's an answer to a question.

Ask "how big is Greenland?" and Mercator's map gives you the wrong answer. Ask "which way do I point the ship?" and it gives you exactly the right one. The trick is knowing which question your map was built to answer.

SOURCES

1. Wikipedia, "Mercator projection." https://en.wikipedia.org/wiki/Mercator_projection (accessed 25 Oct 2026)

2. Wikipedia, "Tissot's indicatrix." https://en.wikipedia.org/wiki/Tissot%27s_indicatrix (accessed 25 Oct 2026)

3. Wikipedia, "Map projection." https://en.wikipedia.org/wiki/Map_projection (accessed 25 Oct 2026)

4. The True Size Of... https://www.thetruesize.com/ (accessed 25 Oct 2026)