New Englanders are among the least-generous people in the nation when it comes to the amount of discretionary income they donate to charity, a new study finds.

The Chronicle of Philanthropy was releasing a study today based on 1997 data from federal taxpayers with adjusted gross incomes of $50,000 or more who itemized deductions. They represent about 18 percent of all U.S. taxpayers but account for nearly 80 percent of the total amount of money donated to charity by individuals.

The study is the first to examine how housing, food, taxes and other costs of living affect the percentage of income donated to charity, the group said. It examined the percentage of discretionary income given to charity.

The eight least-generous large counties are all in New England. Rockingham County, N.H., is at the bottom of the survey with 3.7 percent of its residents’ discretionary income given to charity. Hartford, Conn., was the least-generous metropolitan area in the nation, with 4.7 percent of discretionary income given to charities.

The Providence-Fall River-Warwick, R.I., area was second-cheapest at 5.1 percent, with the Boston-Worcester-Lawrence, Mass., area third at 5.2 percent, the survey found.

“Clearly people in New England, in terms of overall giving, are generally speaking towards the bottom,” said Harvy Lipman, director of special projects for The Chronicle.

Susan Dunn, senior vice president of United Way of the Capital Area in Hartford, said her organization has experienced the generosity of the region. Contributions from the 40 towns in the region her group serves are almost double the national average on a per capita basis, she said.

“What we see in the Hartford region is a very generous community,” Dunn said.

Among residents of large cities, Detroit was most generous with 12.1 percent of discretionary income donated to charity, followed by residents of New York City and Fort Worth, Texas, tied at 10.9 percent.

The Salt Lake City-Ogden, Utah, region ranked first when The Chronicle analyzed giving in the 50 largest metropolitan areas.

The study sheds light on some of the key reasons that people in particular geographic areas give more than those in other areas, The Chronicle said.

Race is one of the major factors, with blacks giving 25 percent more of their discretionary income to charity than whites, the study found. In Detroit, four out of every five middle- and upper-income residents are black; four of the six most-generous large counties have more black residents than the typical American county.

The Chronicle said its study also affirmed previous studies showing the major influence that religious giving has in driving donations.

Among the top 20 counties for giving nationwide, 14 in Utah and Idaho contain a large percentage of Mormons. In those counties, people gave 19 percent to 27 percent of their discretionary income to charity.

Lipman, citing other studies and experts, said the lower percentages of charitable giving in New England may stem in part from religious factors. Noting that most charitable giving is religious, Lipman said people in New England have lower church participation rates than other parts of the country and tend to belong to churches with less stringent requirements for contributions.