The Signal Strength Map is an interactive map of the major cellular networks in the United States, including AT&T, T-Mobile, Verizon, UScellular, and Dish Wireless.

The map is created using signal strength data made public as part of the FCC Broadband Data Collection program.

The FCC requires mobile network operators (MNOs) to fill out Form 477 twice per year, which requests information about where the MNOs offer service with speeds greater than 200Kbps. The MNOs are also required to provide map files of their current coverage areas for each type of network technology they are currently using, 3G, LTE, or 5G, along with signal strength data for each network technology.

The FCC publishes the coverage and signal strength data on its own interactive map:

However, the FCC's map is not the easiest to use.

Each cell phone carrier needs to be manually added to the map to each time you load the page.

And instead of displaying the signal strength data that they collect, the FCC shows all hexagons on the map as the same color. Hovering over a hexagon shows a tooltip for what percentage of the area is covered by the carrier, but it does not tell you if the signal is strong or weak.

Thankfully, the FCC makes the signal strength data publicly available.

We use this signal strength data to power our own Signal Strength Map, and we provide you with the full detail the dataset offers. Here is the same section of Longmont, CO as shown on our map:

Darker green hexagons indicate areas where signal strength is strong and darker red hexagons indicate areas where signal strength is weak.

Our Data Correction Algorithm

In addition to giving consumers a more granular look at the signal strength data from the FCC, we also work hard to make the data as accurate and comparable as possible.

The data is calculated and submitted directly from the cell phone carriers, and it turns out each carrier calculates their coverage metrics differently, making it challenging to compare raw data between the carriers.

To fix this, we run an internal correction and aggregation algorithm to attempt to normalize the data among all carriers.

Our internal algorithm works by grouping hexagons together to form larger hexagons, averaging the estimated minimum signal strength, and comparing tower propagation characteristics to correct and normalize the signal strengths among the carriers.

Our algorithm is not perfect, but it helps fix potential inaccuracies in the data and create an overall more accurate and comparable map.