Last month I shared a free property comparable sales API covering 11 markets.
Since then, we shipped two updates worth talking about: a new US market (Washington DC) and rental yield data baked into the stats endpoint.
The Problem
If you're building real estate tools, getting comparable sales data is step one. But investors always ask the same follow-up: "What's the yield?"
Answering that requires a second data source — rental data — and a calculation layer. Most developers either hardcode national averages (inaccurate) or pay for expensive rental APIs (overkill for a yield estimate).
What We Built
The /v1/stats endpoint now returns gross rental yield for all 6 US markets, derived from two federal data sources:
- Census ACS 5-Year Survey** (primary) — median rents by ZIP and bedroom count
- HUD Small Area Fair Market Rents (SAFMR) FY2026** (fallback) — published annually per ZIP
No extra API call. No separate subscription. Yield comes back in the same stats response you're already using.
Example
bash
curl "https://api.nwc-advisory.com/v1/stats?market=dc&zip_code=20001&months=12" \
-H "X-RapidAPI-Key: YOUR_KEY"
Response:
{
"area": "20001",
"period": "12 months",
"stats": {
"median": 760000,
"count": 745
},
"monthly_rent_estimate": 3167,
"gross_yield_pct": 5.0,
"yield_source": "safmr",
"beds_used_for_yield": 2,
"median_price_per_sqft": 639,
"by_type": {
"Row House": { "median": 913000, "count": 178 },
"Condo": { "median": 635000, "count": 456 }
}
}
One call gives you: median price, transaction count, price per sqft, breakdown by property type — plus monthly rent estimate, gross yield percentage, and the data source.
Bedroom-Specific Yields
Pass min_beds to refine the yield to a specific segment:
3-bedroom yield in DC
curl "https://api.nwc-advisory.com/v1/stats?market=dc&zip_code=20001&min_beds=3&months=12"
This does two things:
1. Filters comparable sales to 3+ bedroom properties
2. Uses the 3-bedroom rent bracket from SAFMR/Census instead of the default 2-bedroom
The response includes beds_used_for_yield: 3 so you know which bracket was applied.
How the Yield Is Calculated
gross_yield = (monthly_rent × 12) / median_sale_price × 100
- monthly_rent comes from Census ACS (preferred) or HUD SAFMR (fallback), matched by ZIP + bedroom count
- median_sale_price comes from actual government-recorded transactions in the search radius
- This is gross yield — before expenses, vacancy, or taxes
The formula is intentionally simple. Investors apply their own expense ratios on top.
New Market: Washington DC
We added DC as our 12th market (6th US market). The data comes from the DC Office of Tax and Revenue CAMA system:
- 256,000+ transactions (1979–2026)
- Full property detail: beds, baths, sqft, year built, neighborhood, ward
- 86% of records have complete bedroom/bathroom data
- Updated from DC government's ArcGIS REST API
All 12 Markets
┌────────────────┬──────┬──────────────┬────────────────┐
│ Market │ Code │ Transactions │ Location Param │
├────────────────┼──────┼──────────────┼────────────────┤
│ United Kingdom │ uk │ 31M+ │ postcode │
├────────────────┼──────┼──────────────┼────────────────┤
│ France │ fr │ 8.3M+ │ code_postal │
├────────────────┼──────┼──────────────┼────────────────┤
│ Singapore │ sg │ 970K+ │ postal_code │
├────────────────┼──────┼──────────────┼────────────────┤
│ New York City │ nyc │ 500K+ │ zip_code │
├────────────────┼──────┼──────────────┼────────────────┤
│ Chicago │ chi │ 580K+ │ zip_code │
├────────────────┼──────┼──────────────┼────────────────┤
│ Miami-Dade │ mia │ 417K+ │ zip_code │
├────────────────┼──────┼──────────────┼────────────────┤
│ Philadelphia │ phl │ 290K+ │ zip_code │
├────────────────┼──────┼──────────────┼────────────────┤
│ Connecticut │ ct │ 210K+ │ town │
├────────────────┼──────┼──────────────┼────────────────┤
│ Washington DC │ dc │ 256K+ │ zip_code │
├────────────────┼──────┼──────────────┼────────────────┤
│ Dubai │ dxb │ 1.3M+ │ area_name │
├────────────────┼──────┼──────────────┼────────────────┤
│ Ireland │ ie │ 230K+ │ county │
├────────────────┼──────┼──────────────┼────────────────┤
│ Taiwan │ tw │ 150K+ │ city_en │
└────────────────┴──────┴──────────────┴────────────────┘
Rental yield is available on the 6 US markets (NYC, CHI, MIA, PHL, CT, DC). Yield data for UK, France, and Dubai is available in PDF valuation reports — API exposure for international markets is on the roadmap.
Data Sources
Every transaction comes from an official government registry — not MLS, not scraped listings, not estimates. The key difference: these are actual recorded sale prices, not asking prices or algorithmic valuations.
Yield data comes from federal sources (Census Bureau + HUD) that are updated annually and publicly available. We cache and serve them per-ZIP so you don't have to parse XLSX files from government portals.
Try It
- Free tier: 50 requests/month, no credit card
- Docs: https://api.nwc-advisory.com/docs
- RapidAPI: https://rapidapi.com/NWCA/api/property-comparable-sales
We're adding more US markets — if you're building something that needs specific coverage, let us know in the comments.
All data sourced from government registries. Yield estimates are informational — not financial advice.
● Live Apps
What to see the API/data in action ?? — free property search with PDF reports
US locations:
- Chicago: https://property-chi.nwc-advisory.com
- New York City: https://property-nyc.nwc-advisory.com
- Miami-Dade: https://property-miami.nwc-advisory.com
- Philadelphia: https://property-phl.nwc-advisory.com
- Connecticut: https://property-ct.nwc-advisory.com
- Washington DC: https://property-dc.nwc-advisory.com
International locations:
- United Kingdom: https://property.nwc-advisory.com
- France: https://property-fr.nwc-advisory.com
- Singapore: https://property-sg.nwc-advisory.com
- Dubai: https://property-dxb.nwc-advisory.com
- Ireland: https://property-ie.nwc-advisory.com
- Taiwan: https://property-tw.nwc-advisory.com
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