The study was based on Internal Revenue Service records of people who itemized deductions in 2008, the most recent year statistics were available.
By focusing on the percentage given to charity from discretionary income — the money left over after necessities are paid for — the study aimed to remove variables such as the differing costs of living around the country, Panepento said. The data allowed researchers to detail charitable giving down to the ZIP code, he said.
The most generous state was Utah, where residents gave 10.6 percent of their discretionary income to charity. Next were Mississippi, Alabama, Tennessee and South Carolina. The least generous was New Hampshire, at 2.5 percent, followed by Maine, Vermont, Massachusetts and Rhode Island.
In Boston, semi-retired carpenter Stephen Cremins said the traditional New England ideal of self-sufficiency might explain the lower giving, particularly during tight times when people have less to spare.
"Charity begins at home. I'm a big believer of that, you know, you have to take care of yourself before you can help others," Cremins said.