Shopping for an Unlimited Smartphone Plan? Know Their Limits

The major U.S. carriers are pushing all-you-can-eat data plans, but there’s lots of fine print behind the hype

Confused by those unlimited data plans from AT&T, Verizon, T-Mobile and Sprint? Competitive eater Carmen Cincotti helps WSJ's Joanna Stern explain the ups and downs of an all-you-can-eat deal.

Riddle me this: What is unlimited, can be upgraded to extra unlimitedness, yet has limits?

Answer: The “unlimited”—but not quite unlimited—plans offered by America’s leading cellular carriers.

This past year, there’s been a seismic shift in the way cellular data is sold. While carriers previously pushed shared data buckets (12GB for the whole family!) with incentives (roll over unused data!), they have moved to plans with data that just doesn’t run out. And video, the culprit eating most of our data to begin with, is at the center of all these deals.

AT&T has two new plans out this week—Unlimited &More and Unlimited &More Premium. Verizon offers three—GoUnlimited, BeyondUnlimited and AboveUnlimited. (Nothing says “not exactly unlimited” like those names.) T-Mobile and Sprint, the network underdogs, have better prices and fewer hitches.

It’s a lot like the move away from cellular minutes way back when. (Remember “Call me after 9 p.m., when it’s free”?) We still pay for the unlimited calls and texts—they’re just baked into the cost of the plan. Now, gigabytes upon gigabytes of LTE data can be baked in, too.

Sounds great, right? That depends. American smartphone owners on limited plans use an average of 4.3GB a month, according to consumer-tracking service NPD, and don’t need an endless data fountain. Plus, AT&T and Verizon’s unlimited plans tend to be more expensive than the lower-end, shared a-la-carte plans still offered. (T-Mobile and Sprint have really gone all-in on unlimited.)

It’s the classic all-you-can-eat-buffet dilemma. Eat your money’s worth, you win. Eat beyond your money’s worth—like competitive eater Carmen Cincotti in the video above—you win big. Eat less, you lose to the behemoth carrier.

Your Data Consumption

Open your phone’s cellular carrier app. Verizon, AT&T, T-Mobile, Sprint, it doesn’t matter. Look how much data you used this month or last month.

If your allotment is in the single digits and you didn’t come close to eating through it, you’re probably best sticking where you are. But say you’ve got a bigger bucket of gigabytes. Did you still decide to read a book on the train this morning instead of watching a video, because you were worried about running out of data? Consider switching to unlimited—or even switching carriers.

If you have a single line with Verizon or AT&T, more often than not, it makes sense to go up to unlimited. For instance, AT&T’s 5GB plan is $70 for a single phone line. Its base Unlimited &More plan is $70. (Taxes and assorted mystery fees will of course cost you extra.)

For those with AT&T and Verizon family plans, there are some magic numbers: If you comfortably share between 2GB and 8GB, keep what you’ve got. A couple with two lines who share 8GB on Verizon pay $110 a month. Going up to Verizon’s base GoUnlimited plan would cost them $130 a month.

However, my family currently pays $150 for Verizon’s two-line, 24GB “XXL” plan. Going up to its midtier BeyondUnlimited plan costs us just $10 more a month. (Spoiler: Yes, we’re upgrading.)

Of course, as with that all-you-can-eat buffet, the bigger the portion in front of you, the more you will consume. People with unlimited plans already average 8.4GB of data a month, according to NPD.

AT&T’s and Verizon's apps allow you to see how much data you've used for your billing cycle. Photo: Joanna Stern/The Wall Street Journal
Your Data Choices

OK, so you’ve decided to go unlimited. When weighing the plans, you must know their…limits:

Limited speeds. If you’re in a busy place with lots of others using the network—or you’ve simply burned through the high-speed access your phone plan gives you—your speeds might be reduced. In my overused all-you-can-eat analogy, you’ll get your food, though you might have to wait in line. But...

“Throttling rarely happens,” says Kevin Hasley of RootMetrics, which measures cellular network performance. If you do notice it, it’s likely in the afternoon-evening rush hour when people are trying to find one another.

Limited video quality. Many base unlimited plans (with the exception of Sprint’s) offer video streaming at lower (480p) resolution. Paying more can buy you higher quality (720p or 1080p).

Limited mobile hotspots. If you ever connect your laptop or tablet to your phone for data, you might be limited with data caps and lower speeds.

After digging into all of the major players, T-Mobile’s One Plus offers the best limit-to-perk ratio. At $80 for one line, you get up to 50GB of 4G LTE before any threat of slowdowns. It also includes 10GB of 4G LTE hotspot data and unlimited 720p video streaming.

Verizon and AT&T’s entry-level plans reserve the right to slow down at any point. A step-up plan gets you a threshold of 22GB.

It’s tempting to leap to T-Mobile, but there’s still a reason not to: According to RootMetrics testing, Verizon and AT&T are still ahead on general, nationwide reliability. “If you’re traveling down a highway and get a flat tire,” says Mr. Hasley, “Verizon is your best bet.” And Sprint is, well, Sprint. T-Mobile is in the process of trying to acquire the company, but we don’t know what the future holds.

Just How Unlimited?

The latest smartphone data plans don’t count out every gigabyte. Instead, they offer all the data you can eat… up to a point.

cost

TWO

lineS

one

line

THE LIMITS

THE PERKS

company

PLAN

1080p video, 15GB mobile hotspot, 30+ Watch TV channels, premium channels

Speed might decrease after 22GB

$150

$80

Unlimited &More

Premium*

Speed might decrease after 22GB

720p video, 15GB mobile hotspot

160**

BeyondUnlimited*

85

Speed might decrease after 50GB

720p video, 10GB mobile hotspot, international texting and data, Netflix (with 2+ lines)

80

One Plus*

120

Speed might decrease after 23GB

1080p video, 10GB mobile hotspot, Hulu included

100

Unlimited

Freedom

60

cost

TWO

lineS

one

line

PLAN

company

THE PERKS

THE LIMITS

1080p video, 15GB mobile hotspot, 30+ Watch TV channels, premium channels

Speed might decrease after 22GB

$150

Unlimited &More

Premium*

$80

720p video, 15GB mobile hotspot

Speed might decrease after 22GB

85

BeyondUnlimited*

160**

Speed might decrease after 50GB

720p video, 10GB mobile hotspot, international texting and data, Netflix (with 2+ lines)

120

One Plus*

80

Speed might decrease after 23GB

1080p video, 10GB mobile hotspot, Hulu included

100

Unlimited

Freedom

60

cost

TWO

lineS

one

line

THE LIMITS

THE PERKS

PLAN

company

Speed might decrease after 22GB

1080p video, 15GB mobile hotspot, 30+ Watch TV channels, premium channels

$150

$80

Unlimited &More

Premium*

720p video, 15GB mobile hotspot

Speed might decrease after 22GB

85

160**

BeyondUnlimited*

Speed might decrease after 50GB

720p video, 10GB mobile hotspot, international texting and data, Netflix (with 2+ lines)

120

80

One Plus*

1080p video, 10GB mobile hotspot, Hulu included

Speed might decrease after 23GB

Unlimited

Freedom

60

100

company

Unlimited &More Premium*

PLAN

one line

cost

TWO lineS

$80

$150

1080p video, 15GB mobile hotspot, 30+ Watch TV channels, premium channels

THE PERKS

Speed might decrease after 22GB

THE LIMITS

company

BeyondUnlimited*

PLAN

TWO lineS

one line

cost

$160**

$85

720p video, 15GB mobile hotspot

THE PERKS

Speed might decrease after 22GB

THE LIMITS

company

One Plus*

PLAN

TWO lineS

one line

cost

$120

$80

720p video, 10GB mobile hotspot, international texting and data, Netflix (with 2+ lines)

THE PERKS

Speed might decrease after 50GB

THE LIMITS

company

Unlimited Freedom

PLAN

cost

TWO lineS

one line

$100

$60

1080p video, 10GB mobile hotspot, Hulu included

THE PERKS

Speed might decrease after 23GB

THE LIMITS

* AT&T, Verizon and T-Mobile offer cheaper unlimited plans. We’re comparing the best options. ** You can mix and match Verizon unlimited plans, this is the price for two BeyondUnlimited users. Note: Costs don't include taxes and other fees

Source: the companies

Your Video Appetite

These plans are largely in response to our phones becoming the new TV sets. As our social-media feeds fill up with video clips and as YouTube and Netflix dominate more of our downtime, our cellular consumption keeps rising. Unlimited video streaming, however, is just part of the carrier’s plan to entice you to watch more. All four of the major carriers are reinventing the classic cable-TV bundle for the much smaller screen.

Thanks to its recent acquisition of Time Warner, AT&T’s unlimited plans now include Watch TV, with live and on-demand programming from 30+ channels, such as CNN and TBS. T-Mobile includes a free Netflix subscription with two or more phone lines. Sprint currently includes Hulu. Verizon includes its comparatively lame Go90 mobile video service.

These options—Netflix, Hulu and even WatchTV—are certainly enticing, especially when you consider they could knock $10 to $15 off our growing monthly subscription bills. But they also signal the bigger change in our relationships with these cellular carriers.

Now that we no longer sign binding two-year contracts, and our smartphones can work on multiple networks, competition has fueled aggressive pricing and plans that resemble one another. To get our attention, they dangle huge data quantities and shiny video packages, plus the usual network-quality brags.

But it’s all really just a distraction to keep you from realizing how much your bill is going up. Just remember the rule: Don’t ditch the regular menu for an all-you-can-eat deal unless you’re really hungry.

Write to Joanna Stern at joanna.stern@wsj.com