T-Mobile Fiber 5 Gig: who it’s worth $90 for, and the fine print

The T-Mobile Fiber 5 Gig price is $90 a month, and that requires AutoPay. Taxes and fees come on top. Here’s what the monthly charge covers, according to T-Mobile:

• Symmetrical speeds: uploads run as fast as downloads, which is the big advantage of fiber over cable.
• Equipment: a Wi-Fi router with no monthly rental fee, plus a mesh Wi-Fi extender if your home needs one.
• Setup: professional installation at no extra charge.
• No caps or contract: unlimited data and no annual commitment.
• Perks: access to T-Mobile Tuesdays, the carrier’s weekly deals and freebies.

For a limited time, new 5 Gig customers also get two months of service free, paid back as two bill credits, and $300 in virtual prepaid cards. Those cards arrive within 14 weeks, so don’t expect them in your first bill cycle.

The guarantee locks the price of your internet service, not your whole bill. T-Mobile’s terms leave several things outside the promise:

• third-party services you add on;
• speed or equipment upgrades you choose yourself;
• taxes and fees;
• per-use charges;
• some limited-time promotions.

In plain terms, the $90 for the internet itself is protected. If local taxes or regulatory fees rise, your total can still creep up. And if you later move to a faster tier or add gear, that part isn’t covered. T-Mobile tells customers to read the full terms before signing up, and that’s good advice here.

So why is T-Mobile making a 10-year promise now? Partly because it walked one back earlier this year. When T-Mobile Fiber Home Internet first launched under that name in 2025, its plans came with a five-year price guarantee. In the spring, a revamped lineup dropped the price lock for new customers ahead of an April 30 launch. The new 5 Gig plan brings a guarantee back, and doubles its length, but only on the top tier.

Every T-Mobile Fiber tier now has a price, and the gaps are smaller than you might expect. These are the prices T-Mobile lists in select areas, all with AutoPay and before taxes and fees:

• Fiber 300: $35 a month for a limited time, a $10 monthly saving. Meant for working from home, streaming and smart devices.
• Fiber 1 Gig: $55 a month for a limited time, a $5 monthly saving, with one free month by bill credit and a $100 virtual prepaid card. Includes a mesh extender if needed.
• Fiber 2 Gig: $70 a month, with one free month by bill credit and $300 in virtual prepaid cards for a limited time. Includes a mesh extender if needed.
• Fiber 5 Gig: $90 a month, two free months by bill credit, $300 in prepaid cards and the 10-year guarantee.

Here’s the catch nobody mentions. The cheaper tiers’ discounts are short-term. Back in late summer, T-Mobile advertised 1 Gig at a regular $60 and 2 Gig at a regular $80 before promotions, with the plan renewing at the regular rate afterward. Only the 5 Gig plan comes with the decade lock spelled out in the launch announcement, so over several years the gap between 2 Gig and 5 Gig may shrink.

For most homes, no. Five gigabits per second is far more than one person streaming 4K video or joining a video call will ever use. T-Mobile itself pitches the plan at the most connected households, where many people and devices are online at once.

Where it can make a difference:

• Big uploads: creators sending large video files or backing up photo libraries to the cloud.
• Lots of devices: families with several gamers, remote workers and smart home gear all running in the evening.
• Security cameras: homes sending several camera feeds to the cloud all day.

One practical tip: a single phone or laptop on Wi-Fi usually can’t reach anything near the full speed. You’ll feel the plan most when many devices share it at the same time, or on a computer wired straight to the router. If your household is mostly streaming and browsing, 1 Gig or 2 Gig, with their prepaid cards, is likely the better value. T-Mobile’s own executives frame 5 Gig as giving homes “room to grow” rather than something everyone needs today.

The plan launched across most of T-Mobile Fiber’s existing markets, not everywhere. T-Mobile says it will add more areas over time, but many addresses still can’t get any T-Mobile Fiber at all. The only way to know is to enter your home address on T-Mobile’s fiber site.

You don’t need to be a T-Mobile wireless customer to get these prices. You can keep your phone on another carrier and still sign up. If you do pair fiber with a T-Mobile phone plan, you’ll get access to T-Mix, the carrier’s new customizable wireless lineup, which is due later in November and lets you pick perks such as streaming and gaming services.

T-Mobile is still building out its fiber footprint. It bought the fiber provider Lumos through a joint venture with EQT Infrastructure, and that venture aims to reach 3.5 million homes by the end of 2028. Rivals AT&T and Verizon are pushing fiber hard too, which helps explain why T-Mobile wants a headline-grabbing price promise.

If your address can’t get T-Mobile Fiber, the carrier’s fallback is 5G Home Internet, which runs over its cellular network rather than a cable to your house. For a limited time, those plans start at $30 a month, and eligible customers can get one month free and up to $200 back in virtual prepaid gift cards. Speeds over 5G vary much more than fiber, so it’s a different product, not a cheaper version of the same thing.

Before you switch anything, compare the total monthly cost, including taxes and fees, with what you pay today. And check when your current provider’s promo rate ends, because that is exactly the kind of jump the 10-year guarantee is designed to avoid.