5G is three things wearing one badge

Every carrier's 5G runs across three tiers of radio spectrum. Lower frequencies travel further and pass through walls; higher frequencies carry far more data but barely travel at all. No carrier can give you both at once from the same tower, so all three coexist and your phone connects to whichever it can reach.

Low band is what makes nationwide 5G coverage claims possible. Mid band is what makes 5G worth having. mmWave is a stadium and downtown-core technology that most people will never connect to, despite being the source of nearly every gigabit figure in 5G advertising.

What the carriers call each one

The plain “5G” indicator generally means low band. Each carrier has a separate brand name for its faster mid-band and mmWave layers, and that name is the one worth checking for.

T-Mobile's mid-band layer has the widest footprint of the three, because it acquired 2.5 GHz spectrum through the Sprint merger and deployed it before the others had comparable spectrum to use. Verizon and AT&T bought their mid-band capacity later, in the C-band auction that closed in February 2021 for roughly $81 billion across all bidders, and have been building it out since.

Do you need a special plan to get 5G?

Basic 5G, no. Every current plan from every major carrier and nearly every MVNO includes 5G access at no extra cost, and there is no such thing as a 5G surcharge in the US market any more.

The fast layer is a different question. Some carriers and several MVNOs restrict mid-band and mmWave access to their higher tiers, so a cheap plan can put you on the same towers as an expensive one and still exclude the spectrum that makes 5G fast. This is one of the few remaining places where a plan's price genuinely changes the network you get rather than just your priority on it, and it is rarely stated prominently. If a carrier's fast layer matters to you, check the specific tier before you buy.

Do you need a new phone?

Any phone sold in the last several years supports 5G, but supporting 5G and supporting the fast layers are separate specifications. Mid band and mmWave each require their own radio bands, and cheaper 5G phones commonly ship without mmWave and occasionally without the mid-band frequency your carrier uses. A phone bought for one carrier may also lack the specific band another carrier relies on.

What 5G actually changes day to day

Less than the marketing implies, and in different ways than expected. Streaming, browsing and video calls were already comfortable on LTE; download speed was rarely the constraint. What mid-band 5G changes most noticeably is upload speed and how the connection behaves in crowds — a stadium or a train platform where LTE would collapse. It also makes 5G home internet viable, which is the single largest practical consequence of the whole build-out.

What it does not change is coverage. 5G is layered onto existing networks, not a replacement for them, and the carrier with the best signal at your address before 5G is very likely still the one with the best signal now.