This year’s sharply falling mortgage rates boosted the number of Southern California households that could theoretically qualify to buy an entry-level homes to 257,000, according to a study by a noted consultancy.

I’m no fan of most “affordability” indexes, as they can often make homebuying seem unrealistically difficult for buyers on a budget. Hey, have you ever met a “median” household or seen the “median-priced” home?

But this study, by John Burns Real Estate Consulting LLC, provides solid context to why housing’s shaky outlook may seem brighter this summer. Remember, home sales have been slumping for nearly a year. But 30-year fixed-rate mortgages have gone from nearly 5% to roughly 3.8% in seven months.

I filled my trusty spreadsheet with the study of the financial impact of the mid-year’s cheaper mortgages to potential homebuyers in 131 major U.S. markets. The consultancy looked at households with incomes that could comfortably to buy a residence priced at 80% of the local median-priced home — a discount associated with entry-level pricing. Financing that was assumed was fairly standard for the tight-wallet buyer: a 5% downpayment and private mortgage insurance; plus property taxes. To “qualify” as potential buyer, these housing costs had to be no more than 33% of income.

In Los Angeles, Orange, Riverside and San Bernardino counties, the number of qualified local buyers rose by 15% since November. The regional increase in potential qualified buyers easily outpaced the national growth in affordability — a 6% jump in the 127 markets outside of the four-county area. That gap makes sense: Cheaper financing is a bigger deal to folks in high-priced communities.

Also, let’s not cheer too loudly. Even with this improvement in qualifications, just 33% of SoCal households — that’s 1.98 million — can “afford” a starter home, according to Burns Consulting. That’s far below an estimated combined 56% who can comfortably purchase in the 127 other U.S. markets studied.

That’s quite an “affordability” gap. And here’s how cheaper mortgages impacted “affordability” around the region …

Sign up for The Home Stretch newsletter and its new Bubble Watch edition. Get a twice-a-week serving of hot housing news from around the region! Subscribe here.

Los Angeles County: Added 129,013 qualifying households since November, or 16% growth — the No. 7 largest percentage gain among major markets. Still, just 26.7% of households — 914,115 — can “afford” a starter home, the fourth lowest “affordability” rate.

Orange County: Added 48,244 qualifying households, or 18% — the sixth largest percentage gain. Still, 28.6% of households — 315,057 — can “afford” a starter home — the sixth-worst “affordability” rate.

Inland Empire: Added 79,551 qualifying households, or 12% — the No. 17 percentage gain. Riverside and San Bernardino counties see 50.6% of their households — 753,510 — “affording” a starter home, the No. 33 lowest “affordability” rate.

Ponder the extremes among the 131 markets studied. Monterey had the biggest percentage increase in qualifiers, up 26%. Kenosha, Wisc., fared worst with this math as its number of qualifiers dropped 1% drop since November.

The rate declines left Allentown, Pa., as the most “affordable” market with 77.4% of its households meeting these qualification standards. Can you guess the least “affordable” place?