# Why does Google Maps use the Mercator projection? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [June 24, 2015, 3:53pm UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366 "2015-06-24T15:53:14Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![suranyi](https://avatars.discourse-cdn.com/v4/letter/s/e36b37/32.png) [@suranyi](https://boards.straightdope.com/u/suranyi)\ **Post date:** [June 25, 2015, 5:16pm UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/21 "2015-06-25T17:16:19Z")
> [@Mr\_Downtown](#): > > Already pretty well covered, but to sum up: > > a. It’s a lot easier to do the computer stuff, because everything can be stored in square tiles that always have north at the top. > > b. Nearly all usage is looking at areas so small that the projection is irrelevant. > > At the mapmakers convention a few years ago, we had a frank freewheeling discussion with part of the Google Maps team about this issue, and some folks felt they should have consulted with actual cartographers before making such a far-reaching decision. And there’s new technology—vector tiles—in the slippy map world that may allow on-the-fly reprojection, so you could have one projection when zoomed in to a town, and a different one when looking at an entire continent. It’s not so much that the projection is irrelevant but that Mercator, or at least “Web Mercator” works especially well at small areas. Better than many other projections. Because angles are conserved, and that’s critical at that level. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [June 25, 2015, 7:04pm UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/22 "2015-06-25T19:04:55Z")
> [@thelurkinghorror](#): > > Oh, obligatory: [xkcd: Map Projections](https://xkcd.com/977/) > [@MandaJo](#): > > [xkcd: Map Projections](https://xkcd.com/977/) Some things are so cool they deserve to be reiterated. ---
**Author:** ![RadicalPi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/radicalpi/32/9806_2.png) [@RadicalPi](https://boards.straightdope.com/u/RadicalPi)\ **Post date:** [June 26, 2015, 12:23am UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/23 "2015-06-26T00:23:54Z")
> [@Gorsnak](#): > > If Google were to move away from Mercator they should just jump straight to zooming out to a globe. Anything else is just half measures. Unless your screen is spherical, you’re still going to need some sort of projection. ---
**Author:** ![Kron](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kron/32/12444_2.png) [@Kron](https://boards.straightdope.com/u/Kron)\ **Post date:** [June 26, 2015, 3:27am UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/24 "2015-06-26T03:27:49Z")
I have been surveying and making maps for 16 years now, and that vast majority of my work is all done in Tranverse Mercator projections. Again, it is nice to have North = Up, no matter where you are. Sure, over extremely large areas you are going to have area distortion, but for most general applications it absolutely makes no difference. ---
**Author:** ![Mr\_Downtown](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mr\_Downtown](https://boards.straightdope.com/u/Mr_Downtown)\ **Post date:** [June 26, 2015, 3:58am UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/25 "2015-06-26T03:58:56Z")
> [@suranyi](#): > > It’s not so much that the projection is irrelevant but that Mercator, or at least “Web Mercator” works especially well at small areas. Better than many other projections. Because angles are conserved, and that’s critical at that level. How is “conservation of angles” important to anyone other than a navigator plotting an oceanic voyage? I would guess that fewer than 2 percent of Google Map views are covering an area more than 100 km square. At that scale, the difference between projections is roughly one pixel on your computer screen. ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [June 26, 2015, 1:01pm UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/26 "2015-06-26T13:01:59Z")
> [@Mr\_Downtown](#): > > How is “conservation of angles” important to anyone other than a navigator plotting an oceanic voyage? Conservation of angles is important to anyone using the map for navigation at any scale. I expect that if ahead of me is an intersection where another road meets the road I am on at a right angle, that the map should also show that road intersecting at the same right angle. Conservation of angles is the property that makes that happen, even if I am driving in Oslo. It’s conservation of area that I don’t really care about. If the map projection makes my local area look too big or too small, I can just zoom in or zoom out until it’s an appropriate size for my needs (i.e. showing a few blocks ahead). If it is distorted in any other way, that doesn’t work. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [June 26, 2015, 1:17pm UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/27 "2015-06-26T13:17:09Z")
> [@Gorsnak](#): > > If Google were to move away from Mercator they should just jump straight to zooming out to a globe. Anything else is just half measures. > [@RadicalPi](#): > > Unless your screen is spherical, you’re still going to need some sort of projection. Sure, but it’ll just be one of the humdrum “3D-graphics” projections any computer program uses for displaying supposed 3D-objects. Does that even have a “map projection” name? ---
**Author:** ![Mr\_Downtown](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mr\_Downtown](https://boards.straightdope.com/u/Mr_Downtown)\ **Post date:** [June 28, 2015, 4:16am UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/28 "2015-06-28T04:16:00Z")
> [@leahcim](#): > > Conservation of angles is important to anyone using the map for navigation at any scale. I expect that if ahead of me is an intersection where another road meets the road I am on at a right angle, that the map should also show that road intersecting at the same right angle. I’m curious what kind of car you’re driving that allows you to make 90º turns with utter precision, but would be confused by a turn measuring 86º or 94º. If the wife calls out that you’re to exit from the traffic circle at “9 o’clock” for the Stavanger Highway, you’d be confused to instead find it at 8:42? I repeat my belief that conservation of angles is only important to those navigating by compass bearing across featureless territory. ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [June 28, 2015, 9:43pm UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/29 "2015-06-28T21:43:52Z")
> [@Mr\_Downtown](#): > > I’m curious what kind of car you’re driving that allows you to make 90º turns with utter precision, but would be confused by a turn measuring 86º or 94º. If the wife calls out that you’re to exit from the traffic circle at “9 o’clock” for the Stavanger Highway, you’d be confused to instead find it at 8:42? I think you underestimate the extent to which this affects the angles at northern latitudes. When using a cylindrical projection, you intrinsically have to stretch in the horizontal direction because on the map, all lines of latitude have the same length, but on the globe northern and southern lines of latitude are much shorter than the equator. Mercator adds the exact same stretch in the north-south direction, so that locally everything looks the same, at the expense of increasing the distortion of area in the big picture. Equal-Area projections do the opposite, applying the inverse north-south stretch to preserve the area locally. This means that your east-west scale even farther out of proportion to your north-south scale locally, in proportion of the square of the ratio between the length of the parallel you are at and the reference parallel for the map. Even if we take for granted that we are all smart enough to avoid confusion, it subverts the expectation that the local map should look like a bird’s eye view of your current location. This seems like a really bad property to give up just to make the map look less distorted at the large scales that no one ever uses except for looking at. > [@](#): > > I repeat my belief that conservation of angles is only important to those navigating by compass bearing across featureless territory. And I repost the [link](https://productforums.google.com/forum/#!topic/maps/A2ygEJ5eG-o) I posted upthread in which a Google employee explains that angle distortion is precisely the reason why they stick with Mercator. ---
**Author:** ![suranyi](https://avatars.discourse-cdn.com/v4/letter/s/e36b37/32.png) [@suranyi](https://boards.straightdope.com/u/suranyi)\ **Post date:** [June 29, 2015, 1:33am UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/30 "2015-06-29T01:33:03Z")
> [@Mr\_Downtown](#): > > I’m curious what kind of car you’re driving that allows you to make 90º turns with utter precision, but would be confused by a turn measuring 86º or 94º. If the wife calls out that you’re to exit from the traffic circle at “9 o’clock” for the Stavanger Highway, you’d be confused to instead find it at 8:42? > > I repeat my belief that conservation of angles is only important to those navigating by compass bearing across featureless territory. The angle distortion is far greater than that in equal area projections. It can turn 90 degree angles into 45 degree angles easily. ---
**Author:** ![JRDelirious](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jrdelirious/32/9531_2.png) [@JRDelirious](https://boards.straightdope.com/u/JRDelirious)\ **Post date:** [June 29, 2015, 2:40am UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/31 "2015-06-29T02:40:40Z")
> [@Gorsnak](#): > > If Google were to move away from Mercator they should just jump straight to zooming out to a globe. Anything else is just half measures. When you switch to the overhead-photo view in “new” Google Maps, it uses the Google Earth feature and it \*does \*zoom out to the globe view. But for the roadmap setting, a Mercator or Modified Mercator is good enough for most of the places where the users actually live. ---
**Author:** ![Absolute](https://avatars.discourse-cdn.com/v4/letter/a/b2d939/32.png) [@Absolute](https://boards.straightdope.com/u/Absolute)\ **Post date:** [June 29, 2015, 3:59am UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/32 "2015-06-29T03:59:10Z")
At least they finally fixed it so that it stops you from zooming out further once you can see the entire map, rather than just repeating the globe as a tile pattern so that you end up with six different copies of each continent… ---
**Author:** ![erysichthon](https://avatars.discourse-cdn.com/v4/letter/e/d07c76/32.png) [@erysichthon](https://boards.straightdope.com/u/erysichthon)\ **Post date:** [July 3, 2015, 6:11pm UTC](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366/33 "2015-07-03T18:11:40Z")
> [@Construct](#): > > The real question is why people think that the purpose of a map should not be to usefully describe reality but rather to advance social justice goals. The people who attack Mercator projections tend to use moralistic language (“awful”, “ignorant”) instead of factual claims. > > Also, I’m not really sure how Gall-Peters (and other equal area maps) even promote progressive values. When I first saw it, my first thought was “Wow, Europe is really small. It’s even more impressive that they conquered the world”. In the Google product forums, there are _lots_ of people complaining about Mercator. Many of these complaints are accompanied by a demand that Google switch to that butt-ugly Gall-Peters projection, so I suspect most of them are politically-motivated. They seem willfully unaware that most people use Google Maps to figure out how to get to the restaurant on the other side of town, not to find out how big Greenland is. [Previous page](https://boards.straightdope.com/t/why-does-google-maps-use-the-mercator-projection/723366.md?page=1)