We already know how many years it takes to save up a down payment for a home in Houston, but getting that money together equals even bigger savings down the road than previously thought.

A recent study by real estate site Zillow ran the numbers in 36 of the largest U.S. metros and compared how much Americans spend on rent compared to mortgage payments, and the news for Texas homeowners is especially good. In Houston, homeowners spend 13.9 percent less on their monthly housing than renters do, representing one of the biggest gaps in the country.

According to Zillow, the median monthly mortgage bill (minus taxes and insurance) in Houston is only $814.05, which translates to a homeowner spending only 14.8 percent of their income on their home. Renters, however, shell out 28.7 percent of their income on rent.

In San Antonio, homeowners spend 15.7 percent of their income on an average mortgage payment of $766.37, compared to residents who spend 28 percent of their earnings on rent — a difference of 12.3 percent.

There's an 11.6 percent difference in Dallas-Fort Worth, where homeowners spend 16.4 percent of their income on an average mortgage of $965.74, compared to renters who sign away 28 percent of their income each month.

Austin, however, has the smallest gap at 7.4 percent, with homeowners spending 19.2 percent of their income on a $1,230.13 mortgage, while renters pay 26.6 percent of their income.

The country's biggest discrepancies can be found in New Orleans and Miami-Fort Lauderdale, Florida, which tied at a 16.9 percent gap. In the Miami area, homeowners spend 23.8 percent of their earnings on a $1,122.56 mortgage bill, while renters spend 40.7 percent of their income on rent. In New Orleans, paying the mortgage sets homeowners back only 15.8 percent of their income, compared to 32.7 percent of a renters.

Meanwhile, San Jose and San Francisco in California have gaps going in the opposite direction. Homeowners in San Jose spend 45.8 percent of their income on their $4,766.46 mortgage, while renters spend 34.2 percent — an 11.6 percent gap. And homeowners in San Francisco spend 41.6 percent of their income on a $3,741.22 mortgage bill, while renters spend 38.3 percent, for a difference of 3.3 percent.

Now, the original intent of this Zillow study was to see what level of education is typically needed to afford owning a home in each market, but we found the mortgage and rent numbers way more interesting. But if you're still wondering, a high school diploma or GED is all that's needed in each Texas city.