The Mercator map is accurate for some things and wildly misleading for others. It perfectly preserves angles and compass directions, which is exactly what it was built to do. But it distorts the size of landmasses, and the distortion gets worse the farther you move from the equator. Greenland, for example, looks roughly the same size as Africa on a Mercator map, even though Africa is actually 14 times larger.
What the Mercator Projection Was Designed For
Gerardus Mercator created his famous map in 1569 for one specific purpose: helping sailors navigate. The projection flattens the globe onto a flat surface by treating it like a cylinder wrapped around the Earth. All latitude and longitude lines intersect at perfect 90-degree angles, forming a clean grid. This makes it possible to draw a straight line between two ports on the map and follow that line using a constant compass bearing for the entire voyage.
That straight line of constant compass heading is called a rhumb line. Before GPS, this property was enormously valuable. A navigator could plot a course, read off the compass direction, and sail. No other projection at the time made that so simple. The Mercator map was never intended to show how big countries are relative to each other. It was a navigation tool, and for that job, it remains remarkably effective.
Where the Distortion Shows Up
The core problem is size. To keep those angles and compass bearings intact, the Mercator projection stretches the map horizontally and vertically as you move away from the equator. Near the equator, shapes and sizes are fairly close to reality. But toward the poles, landmasses inflate dramatically. At 60° latitude, an area on the map appears four times its true size. Near the poles, the distortion becomes so extreme that the projection simply can’t show anything above about 84° North or South.
The classic example is Greenland versus Africa. Greenland covers about 836,000 square miles, roughly the size of Saudi Arabia. Africa spans nearly 12 million square miles. On a Mercator map, they look comparable. That visual illusion has shaped how generations of people perceive the world, making northern countries like Canada, Russia, and the Scandinavian nations appear far more dominant than they are in real life, while countries near the equator (most of Africa, Southeast Asia, South America) appear shrunken by comparison.
Cartographers use a visualization tool called the Tissot indicatrix to measure this effect. It places identical circles at regular intervals across a map. On a Mercator projection, the circles near the equator stay small, but they balloon as they approach the poles, making the size distortion impossible to miss.
What It Gets Right
The Mercator projection is what cartographers call “conformal,” meaning it preserves local angles. The shape of a small area, like a city or a coastline, looks correct. The scale changes across the map, but at any given point, it changes at the same rate in every direction. This means a square kilometer in Norway is stretched equally in all directions, so it still looks like a square, just a bigger one than it should be.
This property also explains why every major web mapping service, including Google Maps, Bing Maps, and OpenStreetMap, uses a variant called Web Mercator. When you’re zoomed in on a neighborhood or a city, the size distortion is negligible and the preserved angles keep streets and buildings looking correct. It also tiles neatly into the square grid that digital maps rely on. For local navigation and street-level browsing, it works well. The problems only become obvious when you zoom out to see the whole world.
Shortest Routes Look Wrong on Mercator
There’s another way the Mercator map misleads people. The shortest path between two distant points on Earth is a great circle route, the arc you’d trace by stretching a string taut across a globe. On a Mercator map, that shortest path appears as a curve that bows away from the equator. Meanwhile, a straight line drawn on the map (the rhumb line) is actually a longer route, because it follows a constant compass heading rather than the true shortest distance.
This is why flight paths on a flat map often look strange. A flight from New York to Tokyo appears to curve far north over the Arctic, which seems like a detour. On a globe, that arc is the most direct path. The Mercator map makes the efficient route look curved and the inefficient route look straight. At higher latitudes, the gap between the two paths grows larger because the map’s meridians are spread apart more than they are on the actual Earth.
Alternative Projections and Their Trade-Offs
No flat map can perfectly represent a sphere. Every projection sacrifices something. The question is which sacrifice you’re willing to make.
The Gall-Peters projection is the most common counterpoint to Mercator. It’s an equal-area map, meaning every country’s size is proportional to its real surface area. Africa looks enormous (because it is), and Greenland shrinks to its proper proportions. The trade-off is that shapes get badly distorted. Countries near the poles appear squashed, and equatorial regions look stretched vertically. It solves the size problem but creates a shape problem.
In 2017, Boston Public Schools made headlines by switching from Mercator to Gall-Peters maps in classrooms, explicitly framing it as an equity issue. With 86 percent of the district’s students being students of color, administrators argued that Mercator maps visually minimized the regions many students’ families came from. The shift was part of a broader effort to present a less Eurocentric curriculum.
The projection most cartographers now consider the best compromise is the Winkel Tripel. Designed in 1921 by German cartographer Oswald Winkel, its name comes from the German word for “triple,” reflecting its goal of minimizing three types of distortion: area, direction, and distance. A study by mathematicians David Goldberg and J. Richard Gott III found it produced less overall distortion than any other projection they tested. National Geographic adopted the Winkel Tripel as its standard world map projection in 1998, and many textbooks and educational institutions followed. It’s not perfect at any single property, but it’s the least wrong overall.
Why It Still Matters
The Mercator projection has been the default mental image of the world for most people in Western countries for centuries. That mental image carries consequences. When northern landmasses look disproportionately large, it subtly reinforces the idea that those regions are more important. Countries along the equator, home to most of the world’s population and biodiversity, are visually diminished.
The map itself isn’t dishonest. It does exactly what Mercator designed it to do in 1569. The problem is using a navigation chart as a general-purpose picture of the world. For zoomed-in digital maps and marine navigation, Mercator remains the right tool. For understanding the relative size of countries and continents, it’s one of the worst options available.