Brian McKay
Brian McKay
Founder & Data ArchitectBrian is the Founder of MonitorBankRates.com. For over 18 years, he has engineered proprietary systems that aggregate 13,738 daily rate quotes from 2,203 financial institutions.
MBR Housing Affordability Index — Methodology
The MBR-HAI is the first housing affordability index updated daily using live mortgage rates from over 13,738 verified rate quotes across 2,203 U.S. banks and credit unions. While the NAR Housing Affordability Index publishes once per month using estimated rates, the MBR-HAI reflects what lenders are actually offering today — giving buyers, journalists, and researchers a real-time read on affordability the moment rates move.
What the MBR-HAI Measures
The MBR Housing Affordability Index answers one question: how affordable is homeownership in this market, relative to the national average? A score of 100 equals the national baseline. A score of 80 means homeownership is moderately less affordable than average. A score of 120 means it is significantly more affordable.
Unlike single-metric indexes that only compare income to mortgage payments, the MBR-HAI incorporates the full cost of ownership — property taxes, total housing costs, and what share of households are actually experiencing cost burden — alongside market supply signals like homeownership and vacancy rates.
The index is anchored to a fixed national reference baseline computed at the long-run reference rate of 6.5%. This means the index moves when rates change, allowing daily tracking of how affordability shifts as the Federal Reserve acts, bond markets move, or lender competition changes.
Score Interpretation
| 120+ | Highly affordable — well above national average |
| 110–119 | More affordable than the U.S. average |
| 90–109 | Near the national average |
| 70–89 | Moderately less affordable |
| 50–69 | Significantly less affordable |
| Below 50 | Among the least affordable markets in the U.S. |
Daily updates
Actual verified bank rates
National + 51 states
Taxes & cost burden included
Monthly updates
Estimated rates
National + metros only
Payment-to-income only
How the MBR-HAI Is Calculated
The MBR-HAI uses a qualifying income method as its primary rate component — the same approach used across standard housing affordability research — then blends in eight additional Census-derived components. The 28% qualifying income threshold aligns with conventional mortgage underwriting standards. This gives the index meaningful rate sensitivity while incorporating far more dimensions of affordability than single-metric indexes.
Component Weights
The Core Formula
Qualifying_Income = (Monthly_P&I / 0.28) × 12
Local_Ratio = Local_Income / Qualifying_Income
All 9 Components
| Component | Category | What It Measures | Data Source | Update Frequency | Weight |
|---|---|---|---|---|---|
| Qualifying income burden | Rate & Income | Monthly P&I vs. qualifying income threshold relative to national ratio at reference rate | MBR live rate database + Census B19013 | Daily | 25% |
| Rate spread | Rate & Income | Current live rate vs. long-run reference rate of 6.5% | MonitorBankRates.com, 13,738 daily verified rate quotes | Daily | 10% |
| Price-to-income ratio | Home Value | Median home value divided by median household income, vs. national PTI | U.S. Census Bureau, median home values and household income | Annual | 15% |
| Conforming limit access | Home Value | Whether 80% LTV of median home exceeds FHFA conforming limit (jumbo territory) | FHFA 2026 county-level conforming loan limits | Annual | 10% |
| Median owner costs | True Cost | Selected monthly owner costs (mortgage, taxes, insurance, utilities) as % of income | U.S. Census Bureau, selected monthly owner costs | Annual | 10% |
| Property tax burden | True Cost | Median annual property taxes (mortgage holders) vs. national median | U.S. Census Bureau, median real estate taxes paid | Annual | 10% |
| Homeownership rate | Market Conditions | Owner-occupancy rate as a signal of market accessibility | Census CPS/HVS Q4 2025 | Quarterly | 5% |
| Homeowner vacancy rate | Market Conditions | Available housing supply signal — low vacancy pushes prices up | Census CPS/HVS Q4 2025 | Quarterly | 5% |
| Owner cost burden | Reality Check | % of mortgage holders spending 30%+ of income on housing (federal cost-burden threshold) | U.S. Census Bureau, owner housing cost burden | Annual | 5% |
| Renter cost burden | Reality Check | % of renters spending 30%+ of income on rent — measures full housing ecosystem stress | U.S. Census Bureau, renter housing cost burden | Annual | 5% |
Why Daily Rates Change Everything
Every other housing affordability index in the United States uses estimated or lagged mortgage rates. The NAR publishes its index once per month, using Freddie Mac's weekly Primary Mortgage Market Survey as its rate input — meaning the index can be 4–6 weeks behind actual market conditions at any given time.
MonitorBankRates aggregates over 13,738 verified mortgage rate quotes from 2,203 lenders every night. These are not estimated rates, not rate sheet averages, and not teaser rates — they are actual quotes verified directly from official institution websites by our proprietary aggregation systems and dedicated team of rate updaters. When the Federal Reserve acts, when bond markets move, or when lender competition intensifies, our database reflects it by the next morning — and so does the MBR-HAI.
A 0.25% change in the national 30-year average shifts the MBR-HAI by approximately 0.8–1.0 index points nationally. In markets where affordability is already near the threshold — like Nashville or Phoenix — that shift can move a market from “near national average” to “moderately less affordable” in a single week.
Rate Sensitivity by Market Type
Data Sources & Update Schedule
30-year fixed mortgage rates computed nightly from 13,738 verified rate quotes across 2,203 FDIC-insured banks and NCUA-chartered credit unions reporting nationally. Every rate is sourced directly from official institution websites — not from rate sheets, published averages, or third-party estimates. Each quote is time-stamped and institution-attributed for full transparency.
ACS 5-Year Estimates (2020–2024 vintage). Median home values, median household income, selected monthly owner costs, property taxes, and owner/renter cost burden percentages. National, state, and city-level data for 27,000+ places. Updated each December when Census releases new ACS estimates.
data.census.gov →Current Population Survey / Housing Vacancies and Homeownership (CPS/HVS). National and state homeownership rates and homeowner vacancy rates. Quarterly data. Current vintage: Q4 2025.
census.gov/housing/hvs →FHFA 2026 conforming loan limits at the county level. Used to determine whether median home buyers in a given market enter jumbo loan territory, which triggers stricter qualifying requirements and a rate premium. Current baseline: $832,750.
fhfa.gov →Frequently Asked Questions
What is the MBR Housing Affordability Index?
How is the MBR-HAI calculated?
How is the MBR-HAI different from the NAR Housing Affordability Index?
What does a score of 100 mean?
How often does the MBR-HAI update?
Can I download the MBR-HAI historical data?
Why does the index include property taxes and cost burden data?
Press & Research Inquiries
Journalists and researchers are welcome to cite the MBR-HAI. Please link to this methodology page and credit data as “MBR Housing Affordability Index, MonitorBankRates.com.”
Contact Us →Explore the MBR-HAI
