How nursing home star ratings really work

Every Medicare- or Medicaid-certified nursing home in the United States gets a rating of one to five stars from the Centers for Medicare & Medicaid Services (CMS). You can look up any facility's rating for free on Medicare's Care Compare website. Five stars means a facility performed much better than average compared with other facilities. One star means it performed much worse than average.

The overall star rating is not a single grade. It is built from three separate ratings, called domains:

• Health inspections — results from on-site surveys by trained state inspectors
• Staffing — how many nursing hours the facility provides per resident per day
• Quality measures — statistics about resident health, such as falls, pressure sores, and hospital visits

Each domain gets its own one-to-five-star rating, and CMS combines them into the overall rating using a set formula. Understanding how that formula works — and where each domain's data comes from — helps you read the stars the way they were meant to be read: as a starting point for comparison, not a final verdict.

The three domains rely on very different kinds of evidence. Some of it is collected and verified by independent parties. Some of it is reported by the facility itself.

This is why we suggest a simple rule throughout this site: give more weight to inspection findings than to self-reported quality measures. Inspections are the only domain where an outside professional walks through the building, watches care being delivered, and documents problems firsthand. Self-reported data can be accurate, but the facility controls what gets recorded.

Here is the part of the system that surprises most families: the health inspection rating is not an absolute grade. It is a ranking against other nursing homes in the same state.

CMS scores each facility based on the problems (called deficiencies) found during its last three annual inspection cycles, plus inspections triggered by complaints. More recent inspections count more than older ones, and more serious or widespread problems add more points. Lower scores are better. Then CMS lines up all the facilities in each state from best score to worst and assigns stars by fixed percentages, roughly:

• The top 10% of facilities in the state get 5 stars
• The middle 70% are spread across 2, 3, and 4 stars (about 23% at each level)
• The bottom 20% get 1 star

This means a set share of each state's facilities gets each star level, no matter how good or bad the state's nursing homes are as a group. Two important consequences follow:

• Stars don't compare well across state lines. A 4-star facility in one state could have an inspection record that would earn 3 stars in a neighboring state, because each state is curved separately.
• Not every good facility can get 5 stars. Even if most facilities in a state performed well, only about one in ten can receive the top inspection rating.

CMS designed it this way partly because inspection practices vary from state to state, so comparing raw scores across states would not be fair. The trade-off is that the stars tell you how a facility ranks among its in-state peers, not how safe it is in absolute terms.

Staffing matters because research consistently links more nursing time per resident with better care. The staffing rating looks at registered nurse (RN) hours and total nurse staffing hours (RNs, licensed practical nurses, and nurse aides) per resident per day, adjusted for how sick or dependent the facility's residents are. A facility caring for residents with heavier needs is expected to staff at higher levels, so the adjustment keeps comparisons fair.

Since 2018, this data has come from the Payroll-Based Journal system, which requires facilities to submit staffing records tied to payroll. That was a major improvement over the old system, where facilities simply wrote down their own staffing numbers around inspection time. Payroll data can be audited, and CMS checks it against other records, so the staffing rating sits closer to the "verified" end of the spectrum than quality measures do.

One thing to keep in mind: staffing levels are averages over time. A facility can look adequately staffed on average but still run thin on weekends or overnight. Care Compare now shows weekend staffing and staff turnover, which are worth a look when you compare facilities.

The quality measure (QM) rating summarizes a set of statistics about resident outcomes — things like the percentage of residents with pressure sores, serious falls, urinary tract infections, or worsening ability to move around, plus rates of hospitalizations and emergency room visits.

Most of these measures come from the Minimum Data Set (MDS), a detailed assessment that facility staff fill out about each resident. A smaller number come from Medicare claims, which the facility does not control directly. Because the facility itself records most of the underlying data, the QM rating is the most self-reported of the three domains. Federal audits and research studies have found that some self-reported measures understate problems compared with what inspectors and claims data show.

That does not make the QM rating useless. Big differences between facilities can still be meaningful, and the claims-based measures (like rehospitalization rates) are harder to shade. But when a facility shows five stars on quality measures and a weak inspection record, trust the inspection record more. Inspectors saw the building; the QM numbers largely came from the facility's own paperwork.

CMS builds the overall star rating with a step-by-step formula:

1. Start with the health inspection rating. This is the base, which reflects CMS's own judgment that independent inspections are the most reliable evidence.
2. Adjust for staffing. A strong staffing rating (4 or 5 stars, and higher than the inspection rating) adds one star. A 1-star staffing rating subtracts one star.
3. Adjust for quality measures. A 5-star QM rating adds one star. A 1-star QM rating subtracts one star.

The overall rating always stays between one and five stars, and CMS limits how far a facility with a very poor inspection rating can climb: a facility with a 1-star health inspection rating cannot be rated higher than 2 stars overall, no matter how good its other domains look. Facilities in CMS's Special Focus Facility program — those with a history of serious, persistent problems — also face caps.

The practical takeaway: the overall star is mostly the inspection star, nudged up or down. A facility can gain up to two stars over its inspection rating through strong staffing and quality measures — which is exactly why it pays to click past the overall number and see where each star actually came from.

Families are often puzzled when a facility's latest inspection looks clean, yet the facility shows two or three stars. There are several honest reasons for this, and none of them require anything to be hidden:

• The rating covers three years, not one. The inspection score includes the last three annual survey cycles plus complaint inspections, with older results weighted less but still counted. A rough inspection two years ago can hold the rating down even after a clean recent survey.
• The curve limits the top. Because only about the top 10% of facilities in each state get 5 inspection stars, a facility with a modest number of minor deficiencies can land in the middle of the pack — 2 to 4 stars — simply because other facilities in the state scored better.
• Staffing or quality measures pulled the overall rating down. A facility with decent inspections but 1-star staffing loses a star from its overall rating.
• Ratings update on a schedule. A recent improvement may not be fully reflected yet, since inspections happen roughly once a year and ratings are refreshed periodically.

The reverse is also true and worth remembering: a facility can hold a decent overall rating while its most recent inspection found real problems, because older, cleaner surveys are still averaging in. Either way, the fix is the same — read the actual inspection reports rather than relying on the star alone. Our guide on how to read nursing home inspection reports walks through exactly what to look for.

Star ratings are a useful screening tool, not a decision-maker. A sensible way to use them:

• Compare within your state only. The inspection curve makes cross-state comparisons unreliable.
• Look at the three domain ratings, not just the overall star. Two facilities with the same overall rating can have very different strengths.
• Weight inspections heaviest, staffing next, self-reported quality measures last. That ordering follows how independently each domain is verified.
• Read the recent inspection reports for any facility on your short list, paying attention to the severity and scope of each deficiency.
• Visit in person, ideally more than once and at different times of day, including a mealtime or a weekend.

No rating system can capture how a facility will care for your family member. But once you know that the stars start with a state-curved inspection ranking and get adjusted by staffing and self-reported measures, you can read them for what they are — a well-organized summary of public records that you can, and should, check for yourself.