Houston has long been a place where it makes more sense to own a home than to rent. That’s still the case, but the math on renting versus owning is changing.

Today, it’s 42.5 percent cheaper to own a home than to rent in Houston, down from 50 percent a year ago.

Why? Higher mortgage rates, along with the combination of rising home values and lower rents. Despite the oil slump, Houston’s median home value ($175,934) is up 3 percent in 2017 compared with last year. The median rent ($1,550) is down 6.1 percent.

These calculations assume homeowners stay in their homes seven years and are able to to put down 20 percent on a 30-year fixed-rate mortgage.

Under those conditions, the truth is that it is still cheaper to buy than rent in all of the 100 biggest U.S. metro areas, but that gap has dwindled recently as price growth outpaces rent growth. And in some markets small changes – a higher interest rate, less money down or a neighborhood’s characteristics – may make a rent versus buy decision too close to call.

The financial advantage of buying versus renting has decreased in all of the 100 biggest metros from the same time last year because mortgage rates have increased slightly, rent growth has slowed or hasn’t changed in 93 metros, and home values have increased in all 100 metros. It soon could be cheaper to rent in San Jose (if interest rates rise to 4.7 percent), San Francisco (5.1 percent), and Honolulu (5.3 percent).

Renters looking to stay in one place for at least seven years and who have saved enough for a 20 percent down payment should not hesitate to buy in metros in the South, such as Houston, Baton Rouge, or New Orleans.

Additionally, Detroit and Philadelphia also are markets where buying far outweighs renting. Here, home seekers find it at least 45 percent cheaper to buy than rent.

Buying is less of a deal in metros that frequently appear on the lists of least-affordable or most-expensive places to live. These places are concentrated in California, Hawaii and the Tri-State area of New York, New Jersey and Connecticut. The margin between renting and buying in San Jose, Calif., San Francisco, and Honolulu dipped into the single digits for the first time in the last four years.

As buying a home in Houston is currently 42.5 percent less expensive than renting, the choice is clear.