About
How we know what we publish
LotGrade puts numbers in front of people who make decisions with them. This page says where every one of those numbers comes from, how it is checked, and what would make it wrong.
Written by the people who build it — a small team of technology product designers and real estate developers. Austin Griffith answers the mail: [email protected].
Sources
Where each number comes from
| What | Source | How current |
|---|---|---|
| Zoning rules and definitions | The adopted ordinance — Title 17 of the Municipal Code of Chicago, parsed from the published edition and hosted here in full | Edition current through February 18, 2026 |
| District standards | Transcribed from that ordinance's own bulk and density tables, one row per district, each figure carrying its § citation | Re-read against each new edition |
| Parcels, lots and ownership | Cook County Assessor and City of Chicago open records | Refreshed periodically; the assessor's own lag applies |
| Zoning map amendments | City Clerk records of passed and introduced ordinances | Refreshed periodically |
| Permits, violations, inspections | City of Chicago open data | As published by the city |
No figure on this site is drawn from a secondary summary, a third-party report, or a model's recollection of what a code says. Where something is estimated rather than read — an averaged front setback, a block survey, a comparable sale — the page that shows it says so.
The ordinance
We host the code we cite
Most zoning summaries ask you to take their word for it. Ours links to the text. The full Title 17 is published here — 17 chapters, 146 sections, 293 defined terms — parsed from the adopted edition into an addressable document, so every rule we state can point at the sentence it came from.
That is not a presentation choice, it is what makes the rest checkable. A citation into a document we host either resolves or it does not, and the test suite fails the build when one does not. A claim about a code nobody can open has no such property — which is how published zoning references end up citing sections that do not exist.
The source document's hash is recorded so a future edition can be told from this one. If the city republishes and we have not caught up, the dates above are how you find out.
Checks
What the build refuses to ship
Accuracy on a site like this cannot rest on care alone, because the failure mode is a sentence that was true when it was written and is wrong for the page it now appears on. So the rules are enforced by tests that run before anything deploys:
- Every ordinance citation must resolve. A link to a § that does not exist in the hosted code fails the build. So does a bare §17-… reference left unlinked.
- Generated pages may not assert a shape the data has not confirmed. A neighborhood page cannot say one district dominates unless it does, cannot name an overlay that reaches none of its lots, and cannot link a district to a page that was never built.
- Worked examples must match the rules they illustrate. The figures in the guides are computed from the same rule table the analyzer runs, not typed in beside it.
- Text stays legible on both grounds. Contrast is held to WCAG AA in light and dark.
None of that makes the site perfect, because a check can only compare a figure to the record it came from — never to the world. Every number here inherits whatever is true of its source: the ordinance edition we last parsed, an assessor class that describes a building’s taxable improvement rather than its use, a lot boundary drawn by the county rather than surveyed. Where a source is wrong or out of date we will be wrong with it, confidently, and in the same format as everything else. What the tests do is make one family of mistakes loud instead of quiet, which is the most a build can do.
Limits
What this is not
It cannot tell you
- Whether a use is lawfully nonconforming. A Lot Report does screen use conformity — it reads the assessor's class against the district's use table — but that class describes the taxable improvement, not the legally established use, and no parcel-level use history exists to read. So a “not permitted” verdict means worth checking, never illegal: it cannot tell a grandfathered use from one that was never lawful.
- Where your lot lines actually are. Only a survey does that.
- What a parcel is worth. Estimates are estimates and are labeled as such.
- What the city will approve. Discretionary relief is discretionary.
It will not pretend
- That a summary is the ordinance. The adopted code and the official map govern.
- That an estimate is a reading. The two are marked differently everywhere they appear.
- That coverage is wider than it is. Chicago today; everywhere else is a request, not a roadmap.
- That a correction did not happen. When a figure changes, the reason is in the history.
What is free
The reference costs nothing
The zoning code, the 70 district pages, the 15 guides (7 general, 8 Chicago), the calculator and the neighborhood pages are free and need no account. They are not a trial of anything.
What costs money is the analyzer: one address, the buildable envelope, the adjustments and bonuses it qualifies for, the records behind it and a pro forma. See what a Lot Report includes, or start from the zoning resources.
Questions
Common questions
Who makes LotGrade?
A small team, and a deliberate mix: technology product designers and real estate developers — people who build software alongside people who actually develop property. That is why the analysis is shaped like the questions a developer asks rather than the fields a database happens to hold. Questions, corrections and market requests reach a person, Austin Griffith, at [email protected].
Is any of this legal advice?
No. LotGrade is a screening tool. It tells you what the published rules say about a parcel so you can decide whether to spend real money looking closer. Before you rely on any of it, confirm with a survey, the city, or a zoning attorney — and the deeper into a deal you are, the more that matters.
How current is the zoning ordinance?
The hosted text is the edition current through February 18, 2026. Chicago amends Title 17 constantly — a single section can carry a dozen amendments — so a rule that changed after that date will not be reflected until the next extraction. The edition date is printed on every page of the code.
What happens when you get something wrong?
We fix it and say so. Several figures on this site have been corrected after a reader pushed back, including a rear-setback rule where our own two files disagreed with each other. If a number here does not match what you are reading in the ordinance, tell us — that is the most useful message we get.
Why is only Chicago covered?
Because doing one city properly is the whole claim. The ordinance had to be parsed into an addressable document, every district's rules transcribed and cited, and 612,000 parcels tagged before a single page could say anything specific. That work does not generalize for free. If you develop elsewhere, tell us where you work — demand is what decides the order.
For a real address
Check the real numbers for a real parcel
The fastest way to judge any of this is to check a rule you already know against what we publish. Pick a district, or a parcel you have worked on, and see whether the numbers match.
The analyzer requires an account — you’ll be asked to sign in. The Zoning Field Guide, the zoning code and these guides are free and need no login.