Report: AT&T bests Verizon in raw 4G speed but still lags in LTE coverage

If unadulterated bandwidth is what you’re looking for in 4G phone, then AT&T(s t) is your best bet for a mobile provider, according to a network tests conducted by RootMetrics. AT&T continued to put distance between itself and Verizon Wireless(s vz)(s vod) in LTE performance, clocking average speeds of 18.6 Mbps on the downlink and 9 Mbps on the uplink.

Verizon averaged 14.3 Mbps down and 8.5 Mbps up, according to Root’s new report, but what it lacked in raw speed, Verizon made up for in coverage. Of the 77 markets in which Root performed its own measurements, Verizon had an LTE network up in every one. Meanwhile AT&T’s 4G service was present in only 47 of the 77 at the time Root performed its tests last year. These maps, compiled from Root’s crowdsourced data, show just how far Verizon’s LTE network reaches compared to AT&T and Sprint(s s):

RootMetrics LTE test data

What’s more, Verizon’s coverage within its LTE footprint was much more consistent. When in a Verizon LTE market Root testers found themselves connected to a Verizon LTE signal 93.2 percent of the time, while for AT&T the number was 81.7 percent. We’ve started to see that trend in Root’s city-specific reports: Big Red is reaching further into the suburban and exurban regions of its launch markets than Ma Bell.

But AT&T was quick to point that it has added many more cities since Root compiled its data (Root measured different markets at different times in the second half of 2012). Of the 30 cities where Root found no LTE network, AT&T has since launched networks in 26 of them, AT&T spokesman Seth Bloom said.

Root's most recent results for New York City, where AT&T boasts the fastest LTE connections.
Root’s most recent results for New York City, where AT&T boasts the fastest LTE connections.

Sprint only started its LTE rollout last summer so it’s still far behind AT&T and Verizon. Root’s staggered testing regime found LTE networks in only five of the 77 markets measured last year and in even in those five markets it caught an LTE signal only half the time. When Root did find LTE, Sprint averaged 10.3 Mbps down and 4.4 Mbps up. Sprint’s speeds are generally lower because it is using half the spectrum for LTE that AT&T and Verizon are tapping for their rollouts.

T-Mobile won’t launch LTE until later this year, but Root did measure its HSPA+ network performance. T-Mobile averaged 7.3 Mbps on the downlink and 1.5 Mbps on the uplink.

RootMetrics uses both crowdsourced data — drawn from smartphones loaded with its CoverageMap iPhone(s aapl) and Android(s goog) apps — and professional testing conducted both in vehicles and indoors (For a detailed look at Root’s methodology, check out our video of a recent Root test in Chicago). Root is also working with GigaOM this week at SXSW in Austin to measure the impact that a large conference of mobile savvy users has on city’s mobile data networks.

Correction: An earlier version of this post incorrectly stated T-Mobile’s LTE network will launch next year. T-Mobile’s 4G network will actually go live later this year.