We often talk about battery size, screen resolution, and SoC as factors that determine how much battery life we can get out of our smartphones. But there are other factors at play, and some of them, like the network you’re using your phone on, are quite subtle.

Case in point: Laptop Magazine battery life tests show that devices running on T-Mobile’s network consistently last longer than the same devices on competing networks, sometimes by a big margin. The pattern is visible “again and again across multiple handsets” according to Laptop Mag’s Michael Prospero.

To come to these numbers, Laptop Magazine ran a benchmark consisting of loading 50 popular websites and pausing for one minute on each page, until the battery is drained. The test was repeated on each device-carrier combination, with Wi-Fi, Bluetooth, and NFC turned off and the screen set to the same brightness of 150 nits.

In order to account for the particularities of a specific test location, testers ran the benchmark in New York and Chicago, while ensuring that the phones had at least three signal bars at all times.

T-Mobile came on top in all tests, and in some cases, like the One (M7), it beat the last place by a full three hours.

Why this discrepancy? First, we can’t rule out a flaw in the benchmark – it’s possible that, by coincidence, T-Mobile has better/less congested coverage in the two test locations. A comprehensive test would measure battery life across dozens of locations, both in cities and in rural areas.

Assuming that the test was not flawed, it may be that T-Mobile’s LTE network is less demanding on devices or that T-Mobile loads less bloatware or even device monitoring services on its devices.

Have you ever noticed a difference in battery life across networks?