How narrow is a narrow network, actually

A narrow network has no legal definition. So we measured one. Across 3,927 plan networks in the 2026 federal marketplace, the median network lists 78,839 providers. The narrowest lists 435. The widest lists 291,816. HMO and PPO labels overlap so heavily that the label tells you almost nothing.

By Brett Spain · Published August 18, 2026 · Last updated August 18, 2026

The short version

You are choosing between plans. One says HMO. One says PPO. You have heard that PPO means a bigger network, so you lean that way.

That instinct is mostly wrong, and we can show you why.

We counted the providers inside every plan network sold on the federal marketplace for 2026. Then we sorted them by the plan type printed on the label. The two groups overlap almost completely.

Nobody has defined the word "narrow"

This is the first problem. There is no legal definition of a narrow network.

KFF says so directly. Researchers often draw the line at plans covering fewer than one quarter of the doctors in an area. That is a convention, not a rule (KFF).

Using that line, KFF found 23% of marketplace enrollees were in a narrow-network plan. Seventy percent were in a plan holding half or fewer of their local doctors. Only 4% had a plan with three quarters or more.

So when a plan is described as narrow, ask who is doing the describing.

The rule does not count providers

Here is the second problem, and it surprises most people.

Federal network adequacy rules do not set a minimum number of doctors. CMS judges a plan on how far you have to travel and how long you have to wait.

For 2026 and later years, CMS evaluates marketplace plans against time and distance standards and appointment wait time standards (CMS 2026 Final Letter to Issuers).

That is a reasonable way to regulate. It is also why two plans can both pass and still be nothing alike. A plan can meet every travel standard with a small roster in the right places.

What the labels are supposed to mean

The four common plan types are defined by how they handle care outside the network, not by network size.

An EPO covers services only inside the network, except in an emergency. An HMO usually limits coverage to doctors who work for or contract with the HMO, and generally will not cover out-of-network care except in an emergency (HealthCare.gov).

Notice what is missing from both definitions. Neither says anything about how many doctors are inside.

So we counted them

We took our copy of the 2026 marketplace plan data and the provider network listings attached to it. Then we counted the distinct providers in each plan network.

Here is the whole market in one table.

That is 3,927 plan networks. The widest is 671 times the size of the narrowest.

How many are genuinely small

Percentiles hide the tail, so here is the tail.

Just over a quarter of the plan networks on the federal marketplace list fewer than 50,000 providers. Twenty of them list fewer than 1,000.

The label barely predicts the size

Now the part that should change how you shop. We split the same networks by plan type.

The median PPO network is larger than the median HMO network. That much matches the folk wisdom.

Everything else does not.

Of 2,113 HMO networks, 648 are larger than the median PPO network. That is 30.7% of them. Of 415 PPO networks, 146 are smaller than the median HMO network, which is 35.2%.

Read that again. About a third of HMOs beat the typical PPO on size, and about a third of PPOs lose to the typical HMO.

The HMO range runs from 435 providers to 291,816. A single label covers both ends of the entire market.

What we found in the accepting-patients flag

Network size is only half the question. A doctor who is in the network but closed to new patients does not help you.

The listings carry a flag for that. Here is how it fills out across 1,909,677 provider listings.

Roughly one listing in eight does not say. That is not a small gap when you are trying to plan care.

Why one network keeps repeating

We want to flag something we found rather than smooth it over.

Of the 3,927 networks, 474 return exactly the same count of 291,816 providers. Another 72 land on exactly 224,266.

The most likely explanation is that many plan components share one issuer network. That is normal in this market. But it means the top of our distribution is a handful of large shared networks, not hundreds of separate ones.

Treat the 291,816 figure as one network that many plans point at, not as evidence of broad choice across many carriers.

What to actually do before you enroll

Do not shop on the plan type. Shop on the directory.

Look up your own doctors in the plan's directory before you enroll. Every marketplace plan must link to its provider directory from the marketplace site (KFF).

Then call the office and ask two things. Are you in this plan for the coming year. Are you taking new patients.

We have written before about why the directory itself can be wrong, and that problem is real. But a directory you checked beats a label you assumed.

Where these numbers come from

Source data: CMS Health Insurance Exchange Public Use Files for plan year 2026, loaded into our own database, joined to the provider network listings we maintain. Source URL: cms.gov/marketplace/resources/data/public-use-files Queried: 18 August 2026. Records behind this page: 1,909,677 provider listings mapped to 3,927 distinct plan networks across the 2026 individual medical market on the federal platform.

Four honesty notes. These are our computations, not a CMS publication. A provider count is not the same as a provider count near you, and the federal rule is written around travel time for good reason. Our figures cover the states using the federal platform, so state-run exchanges are not represented. And the shared-network effect described above means the largest values repeat.

Our other live data work is listed on the apps page, and the rest of the writing is on the blog.

Questions people ask

Is a bigger network always better?

No. A larger roster raises the odds your doctor is included, but it says nothing about wait times or travel. Federal review is built around time, distance and appointment waits rather than headcount.

Does PPO mean a broader network than HMO?

Usually, but far less reliably than people assume. In our count of 2026 networks, 648 of 2,113 HMO networks are larger than the median PPO network.

What counts as a narrow network?

There is no official threshold. A common research convention is a plan covering under a quarter of local physicians, and KFF notes there is no formal definition.

How small can a marketplace network be?

The smallest network we counted for 2026 lists 435 providers. Twenty networks list fewer than 1,000.

Does the directory say whether a doctor is taking new patients?

Sometimes. Of 1,909,677 listings we counted, 76.8% say yes and 10.1% say no. The remaining 13.2% do not answer the question at all.

Should I pick my plan based on the network or the price?

Check the network first, then the price. Changing plans is easy during open enrollment. Changing doctors in the middle of treatment is not.