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How building grades work

Every residential building in New York City — 767,871 of them — gets a grade from A to F, recomputed weekly from the city's own published records. The formula is disclosed in full below. There is no editorial judgment per building: the same arithmetic runs on every lot in the five boroughs.

A B C D F

The window

Grades look at the last 36 months of records. A violation from 1997 says nothing about a building today; a vacate order last winter says a lot. The one exception: an unrescinded vacate order from any year still counts, because the units are still vacated.

The signals and their weights

Each record adds penalty points, weighted by how serious city law treats it:

Signal	Source	Points
HPD violation, class C (immediately hazardous)	HPD	7
HPD violation, class B / I	HPD	3
HPD violation, class A	HPD	1
Housing complaint (heat/hot-water weighted up)	HPD	0.4–1
Emergency repair by the city (landlord didn't fix it)	HPD	8
HPD litigation case opened	HPD	6
Court finding of tenant harassment	HPD	+30
Vacate order (25 if since rescinded)	HPD	50
Alternative Enforcement Program (worst-buildings list)	HPD	40
DOB violation	DOB	2
ECB/OATH violation, class 1 / 2 / 3	DOB	6 / 3 / 1
Bedbug-infested unit reported	HPD	1.5
Failed rodent inspection (active rat signs)	DOHMH	3
Rodent complaint to 311	311	0.5
Marshal eviction executed	DOI	4

Normalization — big isn't bad

Raw counts would fail every large building, so points are divided by the building's residential unit count and expressed per 10 units. A building is then compared only against its size peers: 1–5 units, 6–24, 25–99, or 100+.

From points to letters

Within each size band, grades follow the citywide distribution: roughly the cleanest 79% of buildings earn an A (most of New York is fine — the grade is meant to flag the exceptions), and only about 1% — the truly distressed — receive an F. Cutoffs are percentile-based with fixed floors, so a single stray violation cannot cost a small building its A.

What a grade is — and is not

A grade reflects records the City of New York has published: violations, complaints, court cases, inspections. It is not a physical inspection of the building and not a statement about any individual apartment.
Complaint-driven data has reporting bias: tenants who complain generate records; suffering in silence doesn't. A clean grade means no adverse records, which is strong evidence but not proof.
Commercial and non-residential buildings are not graded.
Grades are recomputed weekly as the city refreshes its data — a building that fixes its problems will climb as old records age out of the window.

Grades are opinions generated mechanically from the disclosed formula above, applied to public records as published by the City of New York.

Look up any address to see its grade and full timeline.