Xfinity Mobile Unlimited 5G Plans Get Cheaper (But That's Not The Best Part)

Xfinity Mobile is trimming the cost of its unlimited 5G plans, with Comcast aiming to undercut its better-known rivals as more Americans hunt for lower prices without sacrificing speed. The new Xfinity Mobile unlimited 5G plans still start at $45 per month for one line, but bring down the price of multiple lines as it blends them with the carrier's "By-the-Gig" per-gigabyte option.

Under that system, subscribers can purchase data in advance, based on how much they think they're need. 1GB is $15, 3GB is $30, and 10GB is $60. If users run out midway through the month, they can switch to a higher tier at any time – or, alternatively, switch to a lower tier if their data needs are unexpectedly low.

Now, there's also a more affordable, more flexible unlimited option. As well as $45 for a single line, Xfinity Mobile 5G plans will be $80 for two lines, $100 for three lines, or $120 for four lines. Previously, two lines would cost $90 per month, three would cost $135, and four would cost $180.

The unlimited plans are also included in the switching system, so subscribers will be able to move between them and the "By-the-Gig" options too. Importantly – and arguably best of all – that's done via the Xfinity Mobile app, rather than having to call up and speak to a customer service agent. The unlimited plans can be applied to both phones and – for $45/mo – tablets, too, and Comcast is using Verizon's 4G/5G network along with its own WiFi hotspot network.

There is, as always, some small print to consider. For a start, you'll need to be a post-pay Xfinity Home Internet subscriber in order to qualify for Xfinity Mobile. Meanwhile, though the data may be unlimited, that doesn't mean you'll always be getting 5G speeds: Xfinity Mobile will automatically reduce the speeds after 20 GB of usage per line. That will trim the rates to 1.5 Mbps downloads and 750 kbps uploads.

Video will stream at SD 480p quality on unlimited plans when on a 4G LTE network, unlike on By-the-Gig plans where it streams at HD by default; if you're on 5G, unlimited subscribers will get the highest possible resolution instead. For mobile hotspots, that's limited to 600 kbps downloads when on an LTE connection. If you're on 5G, however, mobile hotspot data is not capped: you'll get whatever fastest rate the connection supports.

Up to ten lines can be activated, per Xfinity Mobile subscriber. It's also possible to include smartwatches on an account – for $10 per line – Comcast says. The new plans are available now, to new and existing users.

[Updated to clarify unlimited tablet plan pricing]