Filed · Sourced · Open for Inspection

How WindMayor computes everything you see.

Every number on every WindMayor surface comes from a public, free, cited source — or it's labeled [ILLUSTRATIVE]. This page is the paper trail. If you can't reproduce a value from the source we cite, that's a bug. Tell us.

The no-fabrication rule. WindMayor will never invent a number to fill a gap. Where data exists, we use it and cite it. Where it doesn't, we write NULL — we don't smooth, we don't extrapolate, we don't estimate. Partial real beats fake complete.

The DSCR formula

DSCR (Debt Service Coverage Ratio) is the single most important number on the site. It answers: does the rent on this property self-fund a typical loan against it? A DSCR ≥ 1.20 is the conventional minimum that lenders underwrite to. The same exact formula is used across military bases, colleges, and Seattle ZIPs:

# Inputs rent # monthly rent in the ZIP — Zillow ZORI home_value # typical home value in the ZIP — Zillow ZHVI rate_30yr # current 30-year fixed mortgage rate — FRED MORTGAGE30US # Net operating income (NOI), monthly × 12 noi = rent * 12 * (1 - 0.05 - 0.06) - home_value * (0.011 + 0.0055) # 5% vacancy + 6% management + 1.1% tax + 0.55% ins/maint # Annual debt service on an 80% LTV, 30-yr fully-amortizing loan rm = (rate_30yr / 100 + 0.0070) / 12 # +0.70% spread above Treasury ann = 12 * rm / (1 - (1 + rm) ** -360) debt = home_value * 0.80 * ann dscr = noi / debt yield_pct = (rent * 12) / home_value * 100 p2r = home_value / (rent * 12)

What we are NOT modeling

HOA fees (varies wildly; would need per-property data)
Local property tax variation (we use a flat 1.10%; some states are 0.3%, some 2.5%)
CapEx / rehab cost — the 0.55% maintenance is a thin reserve, not a CapEx plan
Closing costs, lender fees, points
Refinance or rate reset risk

This DSCR is a screen, not an underwrite. It tells you which markets are worth your attention. The actual deal needs property-specific inputs.

Data sources, by surface

Surface	Field	Source	Status
Military	BAH series (per MHA)	DoD Defense Travel Management Office BAH tables 2013–2026	live
	Installation list	Wikipedia + GlobalSecurity.org; 454 records	live
	troop_count, years_active, acres	Wikipedia infobox + DoD BSR (partial coverage)	38% / 26% / 13%
	Feeder-city ZIP economics	Zillow ZHVI/ZORI by ZIP, FRED 30yr	live
	greater_area_pop, maint_cost_idx	Census ACS B01003 + BLS OEWS / CPI-U (pending)	pending
	bah_yield_{1y,5y,13y}	Derived from BAH series — CAGR over window	pending
Colleges	Institution list, enrollment, tuition, admit, grad rate	IPEDS HD/EF/IC/ADM/GR 2023, NCES public domain; 6,086 records	live
	ZIP economics & DSCR	Zillow ZHVI/ZORI + FRED 30yr	4,413 / 6,086 (72%)
	housing_capacity, % housed on campus	IPEDS IC2023 ROOM + ROOMCAP fields	5,947 / 6,086 (98%)
	pct_off_campus	Derived: 100 − housing_pct_of_enroll	98%
	endowment_per_student	Derived: endowment / enrollment	2,732 / 6,086 (45%)
	Display outlier clamp	Winsorized; raw values preserved in `*_raw` fields	display only
Seattle	ZIP economics	Zillow ZHVI/ZORI + FRED 30yr	66 / 69 ZIPs (96%)
	Recapture / Pre-qual tools	Live FRED rate at page load; no fixtures	live
	Statewide expansion	All WA ZIPs (~400) — pending Y-SEATTLE.wa-expand	pending
Rate	Historical series (annual)	FRED DGS10 (1962–2026), FRED MORTGAGE30US (1971–2026)	live
	"Now" values	FRED latest single observation (daily/weekly), date-stamped	live
	Forecast bands	last_rate ± 1.5 × σ_annual × √t (10-yr rolling σ)	honest envelope
AI / Chip	Public companies, returns, HQ city	Yahoo Finance chart API; public corporate filings	20 cos (expansion pending)
AI / Chip	Private AI HQ list	Public record only (city, no valuations, no individuals)	pending

What does NULL mean?

When you see a blank or — in the UI, that field has no real source value for that record. We do not estimate, smooth, interpolate, or fill from a neighbor. Examples:

A small military installation with no Wikipedia page → troop_count = NULL
A college whose ZIP is not in Zillow's ZHVI universe (truly rural) → dscr = NULL (a future ticket adds city / county fallback)
An extreme outlier (e.g. p2r > 60, or |dscr| > 5) → NULL for display; raw value kept in *_raw field

What does [ILLUSTRATIVE] mean?

Listings on WindMayor.Market currently show illustrative example deals — clearly tagged [Illustrative] — because the marketplace is pre-launch. Once live inventory ships, the tag goes away on real listings. Estimates inside an illustrative listing (rent estimate, DSCR estimate) are bracketed (est) for the same reason.

The rate spine

Every DSCR calculation across all surfaces uses the same FRED MORTGAGE30US rate — pulled live where possible, otherwise the latest observation from the cached rate series. The +0.70% spread above the Treasury is documented OfferMarket pricing for DSCR investor loans, used because investor loans price higher than owner-occupied. The single rate spine means no surface can quietly drift from another.

Display outlier handling

Some IPEDS / Zillow records produce wild values — a college reporting a 29,000% enrollment YoY (probably a coding error), a ZIP with $5M ZHVI and $4k rent (real but breaks the screen). We clamp these for display only:

enrollment_yoy_pct outside [−50, +50]% → NULL in UI
home_value > $3M or rent > $8k/mo → NULL; flag hv_quality / rent_quality = extreme
price_to_rent > 60 or < 5 → NULL; flag p2r_quality = extreme / thin_sample
The raw value is preserved in *_raw so nothing is lost

Sources & attribution

FRED (Federal Reserve Bank of St. Louis): public domain. fred.stlouisfed.org
Zillow Research (ZHVI, ZORI): free public data, used with attribution. zillow.com/research/data
IPEDS (NCES, U.S. Department of Education): public domain. nces.ed.gov/ipeds
DoD BAH (Defense Travel Management Office): public schedule. travel.dod.mil/…/BAH
Wikipedia infobox: Creative Commons Attribution-ShareAlike
GlobalSecurity.org: public publishing, attribution provided
Census ACS (U.S. Census Bureau): public domain
BLS OEWS / CPI (Bureau of Labor Statistics): public domain
Yahoo Finance chart API: public endpoint; attribution per fetch

Disclaimer

WindMayor is a research and underwriting screen, not investment advice, not legal advice, not tax advice. Numbers are screens for further diligence, not closing-grade values. Past data is not prediction. Real deals require property-specific underwriting with current local comparables.