Map: Salt Lake cellular data network performance

The Salt Lake Tribune went to more than 100 spots in Salt Lake County in January to test the 3G and 4G network speed of the four major cellular providers: AT&T, Sprint, T-Mobile and Verizon.

This results map allows you to compare and contrast networks' upload and download speeds for each location The Tribune tested.

The map should initially show the four networks' 3G download speeds. The larger the circle, the better the speed at that test point.

There are several ways to customize the map to show only the information you want.

To add or remove a network's upload or download speeds from your view, click the check box next to it in the Layers window on the right.

If the Layers window is getting in your way, click the green tab connected to it to hide the window.

You may zoom in on the map by using the sliding scale on the left, or you can double-click on a point in the map.

To see the numbers the colored circles on the map represent, click on the "Legend" button on the bottom right of the map (it may be hidden behind the Layers panel, which you can shrink by clicking the green tab). The legend shows the speeds in kilobits per second.

Network speeds are measured in bits per second while file sizes are measured in bytes. Eight bits are equal to 1 byte, and you would need about 8,000 kilobits of data to transmit a typical 1 MB cellphone picture. This would take less than two seconds to upload on average with Verizon 4G, but nearly 13 seconds on average to upload with Verizon 3G.

You can also click on any circle on the map to see a chart with the numbers. (If you prefer to see the full results for each area as a table, use the map attached to the main story instead or go to bit.ly/slccellmap.)

Also, to best compare networks to one another, the scales are adjusted for each category. For instance, the 3G download speeds follow one scale, but 3G upload speeds — which are almost always a fraction of the typical download speed — follow another to better show how each network performed in that area. The speeds for 4G work the same way: downloads on one scale, uploads on another.

So use the circles to compare apples to apples (Verizon's 3G download to T-Mobile's 3G download, for instance) but not to oranges (Verizon's 3G download to Verizon's 3G upload).

To test and share your own results, go to bit.ly/slccelldata. To view other readers' data, go to bit.ly/slccellreadermap.

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Cell network data gathered by Vince Horiuchi. Interactive map created by Jessica Miller.