A data product is only worth what its worst number is worth. This page says plainly what is measured, what is modelled and what is missing.
Coverage is 40,511 ZIP codes across 28,921 cities, and every figure is labelled with where it came from. In cities where we hold collected listings, the rate is the measured median of those listings and the page tells you how many. Everywhere else it is modelled, corrected against the measured set, and labelled as such. We would rather show you a number's provenance than a confident average that hides it.
These are different products at different prices and we never average them together:
A half bath assigned to one room (toilet and basin, no shower) prices between the two and is tracked separately rather than folded into either.
A private bathroom is worth a median +32.7%, and that figure is measured rather than assumed. It is controlled for the property: the comparison is made inside individual houses, so it isolates the bathroom instead of measuring the house and the neighbourhood along with it.
The distinction is not academic. The obvious approach — comparing private-bath rooms to shared-bath rooms across a city — returns a substantially larger number, because private-bath rooms sit in better houses in better areas. An operator pricing an ensuite renovation off that figure would budget for roughly twice the lift they would actually get. Markets with enough data carry their own premium; the rest carry the national figure and say so on the page.
The matching rules, qualifying thresholds and the per-market derivation are documented for subscribers.
Addresses are resolved by the US Census Bureau geocoder — public, free, no account. It returns the ZIP, and the ZIP is what we price. If the exact ZIP is not covered yet, we fall back to the nearest priced ZIP within 40 miles and say so on the result.
Nothing you type is stored or sent anywhere else. The rate table and the zoning research are downloaded to your browser and every calculation runs locally.
The whole-house lease figure comes from HUD Small Area Fair Market Rents, FY2026 — a public dataset giving a 2-, 3- and 4-bedroom rent for roughly 38,600 ZIP codes. It is the only free, national, ZIP-level whole-unit rent that exists.
33 cities so far. Each was read out of the municipal code itself — the ordinance, the definitions section, the use table — and the source is named on every entry. Where a widely repeated figure turned out to come from a superseded ordinance, we say so rather than repeating it.
Two separate counts, from two separate feeds, deliberately never merged. Code-enforcement cases are the city acting. 311 requests are a resident reporting. We count, in each city’s own published register, the records that describe letting by the room or the occupancy problems that come with it, against that register’s total over a stated period. Each city’s register uses its own vocabulary, so the terms are tuned per city and the matched text is sampled by hand before a number ships — a bare keyword count is wrong often enough that we do not publish one.
Complaints per case is computed only where both feeds exist for the same city and their periods overlap by at least five years. Dividing a 311 feed that begins in 2020 by a case register that begins in 1994 produces a number, and the number is meaningless.
Five components, weighted, and every one is shown with the reasoning behind it. Components we cannot compute are marked n/a and dropped from the weighting rather than silently averaged.
| Component | Weight | What it measures |
|---|---|---|
| Regulatory environment | 30% | The zoning verdict for that city, or n/a if unresearched |
| Room-rate strength | 25% | National percentile of the ZIP's shared-bath rate |
| Rate vs. its metro | 15% | The ZIP against its own metro median |
| Private-bath upside | 15% | Dollar spread between private and shared, ranked nationally |
| Market depth | 15% | How many priced ZIPs the metro has — a confidence proxy |
Not modelled, and therefore not in the score: demand and fill speed, stabilised occupancy, competing room supply, and employment access. Those need live listing data the site does not have yet. A score here is a read on rates and rules, not on demand.