How the score works
The Rattiness Score is a single number from 0 to 100. It answers one question: compared to everywhere else in New York City, how thick are the rats where you live? 100 means the rattiest ZIP code in NYC. 0 means the most rat-free.
The data
Every score is built on real 311 rat-sighting complaints from
NYC Open Data
— specifically requests where complaint_type = 'Rodent' and
descriptor = 'Rat Sighting'. We pull the trailing 12 months
(17,693 sightings) and refresh daily. The all-time record we draw
from holds 145,330 reports.
The calculation
- Count every rat sighting in your ZIP code over the last 12 months.
- Divide by the ZIP's land area in square miles (US Census ZCTA data) to get a density — rats per square mile. This is the key step: big ZIPs rack up more sightings just by being big, so raw counts are misleading. Density is fair.
- Rank that density against all 180 eligible NYC ZIP codes.
- Your score is your percentile in that ranking. Score 90 = rattier than 90% of NYC ZIPs.
The fine print
- We exclude ZIPs that are essentially parks, airports, or single buildings (land area under 0.05 sq mi), and ZIPs with fewer than 5 sightings, so a single rat in a tiny area can't score 100.
- This measures reported rats, not all rats. Some neighborhoods complain more than others, and a high score can partly mean "engaged, 311-savvy residents." We think that's still a useful — and very funny — signal.
- The most recent day or two of data is always incomplete (311 has reporting lag), which is why the score uses a full trailing year rather than a snapshot.
- Year-over-year trends compare the last 12 months to the 12 months before that.
- The "on your actual block" numbers are different from the score: when you search a specific address, we count real sightings within ~2 and ~5 blocks (150m / 400m) of that exact spot, using the GPS coordinates the city attaches to each complaint. The 0–100 score is ZIP-level; the block counts are address-level.
The NYC Rat Index
Alongside the per-ZIP Rattiness Score, the site tracks a single city-wide number: the NYC Rat Index. It works like a market index — 100 = 2010 rat levels, the year the city started publishing 311 data. Getting below 100 is the goal: that means citywide sightings have fallen back to or below where they stood when the city began its rat-reduction push.
- The headline is seasonal (trailing 30 days vs. the 2010 daily average), so it runs high in summer — peak rat season — and dips in winter. Don't read too much into month-to-month swings.
- The 12-month figure is the calmer read: a full year of sightings vs. the 2010 full-year count. Use this to judge whether things are actually improving.
- Like the Rattiness Score, the index is built on 311 complaints — a proxy for rat activity and reporting behavior, not a literal census.
Why we built it
The city already maps rat pins. Nobody scored your block, ranked the neighborhoods, or filed a daily dispatch with a sense of humor. So we did. It's built on public data, the math is above, and you're welcome to check our work.