According to a report from Umlaut, T-Mobile has the fastest 5G in Atlanta, Dallas–Fort Worth, Newark-Jersey City, Philadelphia and Phoenix.
This makes ten total major markets where T-Mobile has been proven to have the fastest 5G. The previous five cities were Chicago, Houston, New York City, Washington D.C., and Tampa.
“We have our foot on the 5G gas pedal, and we’re not letting up. T-Mobile has been the leader in 5G coverage from the moment we launched our nationwide network, and now we’re piling on the speed with our super-fast Ultra Capacity 5G rolling out across the country. This is how you build a real 5G network — with great coverage, capacity and speeds — across major cities and into small towns.”
Neville Ray, President of Technology at T-Mobile
The tests spanned over 2,500 square miles and over 8,000 individual test samples. The results show that T-Mobile’s 5G, especially their Ultra-Capacity n41 coverage, is the fastest when compared to the other major carriers.
Atlanta 
Dallas-Forth Worth 
Newark-Jersey City 
Philadelphia 
Phoenix
T-Mobile is by far leading the way with both mid-band and low-band 5G deployment. T-Mobile says their low-band 600Mhz n71 covers 280 million people across 1.6 million square miles, nearly 2.5x more coverage than AT&T and nearly 4x more than Verizon. They also state that their mid-band 2.5Ghz n41 covers 2,400 cities and 106 million people.
Source: T-Mobile
