---
title: "Tiles à la Google Maps: Coordinates, Tile Bounds and Projection | Guides | General"
description: "Learn how zoomable maps work, including coordinates and projections."
---

> For AI agents: a documentation index is available at [/llms.txt](https://docs.maptiler.com/llms.txt). Markdown versions of all pages are available by appending .md to any URL.

    

# Tiles à la Google maps

## Coordinates, tile bounds, projection

Learn how zoomable maps works, why they're typically in Mercator projection, and what coordinate systems they can use.

![Pyramid](https://media.maptiler.com/old/img/tools/pyramid.png)

[Explore map tiles in full screen](https://labs.maptiler.com/showcase/tiles-map-demo/)

## How a zoomable map works

People have been using coordinate systems and map projections to transform the shape of Earth into usable flat maps for centuries.

A map of the entire world is too big to be directly displayed on a computer. Therefore, there is a clever mechanism for quick browsing and zooming on maps: the map tiles.

The world is divided into small squares, each with a fixed geographic area and scale. This clever trick allows you to browse just a small part of the planet without loading the whole map, and you still get an illusion of exploring a single huge document.

## Spherical Mercator

Map projection pioneered by Google, now standardized.

Google Maps was one of the first systems for displaying dynamic maps on the web. They chose a Spherical Mercator projection because it preserves shape and angles. The entire world looks like a square, making it easy to work with on a computer.

 ![spherical mercator graph](https://media.maptiler.com/old/img/tools/mercator-epsg-img.png)

Almost every open source (like OpenStreetMap) and commercial Maps API provider (like MapTiler) are now using this projection and tiling profile. The tiles are therefore compatible with each other.

## Coordinate systems for using global map tiles

![Map of Earth](https://media.maptiler.com/old/img/tools/earth.png)

### **Degrees** Geodetic coordinates WGS84 (EPSG:4326)

**Longitude and latitude** coordinates are used by GPS devices for defining position on Earth using World Geodetic System defined in 1984 (WGS84).

_WGS84 geodetic datum specifies lon/lat (lambda/phi) coordinates on defined ellipsoid shape with defined origin (\[0,0\] on a prime meridian)._

![World displayed using mercator projection](https://media.maptiler.com/old/img/tools/world.png)

### **Meters** Projected coordinates Spherical Mercator (EPSG:3857)

**Global projected coordinates** in meters for the entire planet. Used for raster tile generation in GIS and WM(T)S services.

_Simpler spherical calculations are used instead of ellipsoidal. Mercator map projection deforms size (Greenland vs Africa) and never shows poles._

![Pyramid with explanation of resolution and zoom levels](https://media.maptiler.com/old/img/tools/pyramid2.png)

### **Pixels** Screen coordinates XY pixels at zoom

Zoom-specific **pixel coordinates** for each level of the pyramid. Top level (zoom=0) has usually 256x256 pixels, next level 512x512, etc.

_Devices calculate pixel coordinates at defined zoom level and determine visible viewport for an area which should be loaded from servers._

![map tiles graph](https://media.maptiler.com/old/img/tools/mercator2.png)

### **Tiles** Tile coordinates Tile Map Service (ZXY)

Coordinates of a **tile in the pyramid.** There is one tile on the top of the pyramid, then 4 tiles, 16 tiles, etc. All raster tiles have the same size, usually 256x256 or 512x512 pixels. [Vector tiles work a bit differently](https://docs.maptiler.com/guides/how-maps-work/raster-vector-tiles/).

_Only relevant tiles are loaded and displayed for the area of interest (viewport)._

## Resolution, zoom, and scale

Map resolution defines the level of detail visible on a map at a specific zoom level. For a detailed explanation and examples of what's visible on different zoom levels, see [Map resolution and zoom](https://docs.maptiler.com/guides/how-maps-work/map-resolution/).

[Complete table: Tile size, resolution, scale, zoom](https://docs.maptiler.com/guides/how-maps-work/map-resolution/#table)