About BlockBook

BlockBook is a free property research tool for New York City. Type any NYC address and get the official public record for that building — size, stories, year built, lot dimensions, unit count, zoning, floor area ratio (FAR), the city's assessed value, annual property taxes, and rent-regulation indicators — plus a full mortgage calculator that uses those real numbers instead of guesses.

Data sources

Everything shown on this site is computed from official City of New York open datasets:

• Property Valuation and Assessment Data (NYC Department of Finance) — taxable values, tax classes, and building characteristics.
• PLUTO — Primary Land Use Tax Lot Output (Department of City Planning) — lot and building geometry, zoning, FAR, year built, unit counts.
• DOF Rolling Sales and ACRIS Real Property Master (with ACRIS Legals) — recorded deeds and sale prices.
• DOF Annualized Sales — the city's published sales spreadsheets going back to 2007. The open-data feed only reaches 2016, so these fill in 2007–2015. They are the only sale history available for Staten Island, whose deeds are recorded with the Richmond County Clerk rather than in ACRIS.
• Local Law 7 qualified transactions and Property Exemption Detail — rent-regulation indicators and 421-a/J-51 abatements.
• LPC Individual Landmark and Historic District Building Database — architects, styles, and landmark status.
• Property Tax Rates by Tax Class — the official class rates, refreshed automatically.
• NYC GeoSearch — the city's official geocoder, matching typed addresses to their exact tax lot (BBL).

How taxes are shown

The annual tax figure is the city's current taxable value multiplied by the official tax rate for the property's class. It reflects public assessment records, not the owner's actual bill — abatements and exemptions (421-a, J-51, co-op/condo abatement, STAR) can lower what is actually paid.

Coverage

BlockBook covers the five boroughs of New York City: Manhattan, Brooklyn, Queens, the Bronx, and Staten Island — roughly 860,000 tax lots. Addresses outside NYC are not supported.

Editorial policy and corrections

Every figure on this site is computed directly from the official datasets above — nothing is estimated by hand or copied from third-party sites. Tax rates refresh automatically from the city's published schedule, mortgage rates from Freddie Mac's weekly survey, and research statistics are recomputed daily from the full assessment roll; pages state when their figures were last verified. Guides that cite laws (mansion tax, transfer taxes, 421-a, 485-x, the pied-à-terre tax) are checked against the enacted statute text and the Department of Finance's published rules, and are updated when the rules change.

If you find an error, we want to know: contact info@nycblockbook.com and we'll correct it promptly.