Mercator vs Gall-Peters: which world map is fairer?
Mercator and Gall-Peters take opposite sides of the same problem. Mercator keeps shapes looking right but lets country sizes get way off. Gall-Peters keeps sizes exactly right but stretches shapes out of proportion. Which one is 'better' depends on what you're using it for, and also on a real argument people have had about maps and fairness.
The opposite tradeoff
Mercator keeps every shape looking normal but stretches sizes, especially near the poles. Gall-Peters does the reverse: it keeps every country's true size, but stretches shapes tall and skinny near the equator and squashes them shorter near the poles. Neither one can do both.
Why Gall-Peters countries look stretched
On Gall-Peters, countries near the equator, like those in Africa and South America, get stretched tall and thin, while countries near the poles get squashed short and wide. The true size is honest, but almost nothing looks like its familiar shape.
The Peters controversy
In the 1970s, a man named Arno Peters promoted this map hard, saying maps like Mercator were unfair to countries near the equator because they made them look smaller than they really are. A lot of schools and aid organizations adopted his map to fix that. But many mapmakers pushed back, pointing out the map's own shapes are badly distorted, and that a very similar equal-area map, made by James Gall in 1855, already existed before Peters presented it as new.
What each one is actually good for
Mercator is still the right choice for steering by compass. Gall-Peters is a reasonable choice when you specifically want to make sure no country's true size gets underplayed, even though the tradeoff is that shapes look unusual. Most general teaching maps today, including this site's, use a different equal-area map, Equal Earth, that keeps size honest without stretching shapes as much.
Verdict
Use Mercator when you need true compass directions, like navigation. Use Gall-Peters when the most important thing is that no country's size gets shrunk on the page, and you're okay with shapes looking stretched to get that.
Frequently asked questions
What's the difference between the Mercator and Gall-Peters projections?
Mercator is conformal, keeping shapes and compass directions true while letting area distort, especially near the poles. Gall-Peters is equal-area, keeping every region's true size correct while stretching shapes, especially near the equator.
Why is the Gall-Peters projection controversial?
It was promoted in the 1970s as a fairer alternative to Mercator for representing equatorial nations' true size, which many organizations welcomed. Cartographers objected to its severe shape distortion and to claims made about its originality, since a very similar projection existed decades earlier.
Is the Gall-Peters projection more accurate than Mercator?
It's more accurate for area, since it's equal-area and Mercator is not. It's less accurate for shape, since Mercator is conformal and Gall-Peters badly distorts outlines. Neither is more accurate overall; they're accurate about different things.
Why do countries look tall and skinny on the Gall-Peters map?
To keep area exactly correct on a cylindrical grid, Gall-Peters stretches regions near the equator vertically and compresses regions near the poles horizontally, which distorts their familiar outlines even though their true size is preserved.
Do schools and organizations still use the Gall-Peters map?
Some do, particularly when the point is emphasizing true relative size of equatorial nations. Many teaching maps, including this site's, now default to newer equal-area projections like Equal Earth, which preserve true size with less shape distortion.