Zoom Level: Background Information

When you download a map for offline use, the app allows you to select a zoom level.

Android: Download Maps for Offline Use

iOS: Download Maps for Offline Use

The zoom level you choose represents the level of detail you want to download for that area.  A map downloaded with a zoom level of 18 will have more detail than a map downloaded with a zoom level of 12. 

Numeric map scale refers to the relationship (or ratio) between distance on a map and the corresponding distance on the ground. For example, on a 1:24,000 scale map, 1 inch on the map is 24,000 inches, or 2000 feet, on the ground. Print maps are often referred to by their scale in this way.

"Zoom level" is the digital equivalent of "numeric map scale".

Calculating the numeric map scale for a digital display is more complicated because it involves the screen size and resolution, which is different for every device.   

Furthermore, digital maps can be either raster or vector, which have different display properties.

Raster maps are constructed of a grid of images, with different images for different zoom levels.  Most of the maps in Gaia GPS are raster maps. This is why when you zoom all the way in on some map sources, the labels become large and fuzzy. For example, USGS Topo is a raster map:

Vector maps are composed of points and lines. As you zoom in, a vector map is "lossless" -- it does not get blurry. Instead, the different components of the map like contour lines, hillshading, and labels can all operate on independent scales. This allows you to zoom in on an area and retain size and clarity of labels and other POIs. Here is Logan Pass at the same zoom level as USGS Topo using the recently updated Gaia Topo: 

You can read more about this in How Do Maps Work in Gaia GPS?

Because vector maps are made of multiple components, numeric map scale is more complicated to calculate for a vector map and so the scale displayed for downloaded vector sources is an estimate.

Raster Map Zoom Level

The table below is an approximate reference for how the zoom level corresponds to the numeric map scale for a raster map.  We recommend experimenting to see what zoom level works best for you, but find that a zoom level of 14 or 15 is adequate for most outdoor activities.

Vector Map Zoom Level

As mentioned above, vector map scale is more complicated. But for sources based on Gaia Topo, the maximum zoom of 12 approximately corresponds to a 1:8,000 scale.