More than two-thirds of Germans said they always tip when leaving a restaurant or hotel on vacation, compared with 57 percent of the 1,600 Americans questioned.
Cultural uncertainty may be the reason for the surprise reticence of Americans when tipping abroad. TripAdvisor found that more than 80 percent of Americans were sometimes uncertain about how much gratuity to leave, with three-quarters checking travel guides for advice. In addition, 112 of the Americans surveyed said they took a tip conversion sheet with them when abroad.
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Despite these preparations, three percent of Americans said tipping difficulties had "ruined" their vacation, citing staff asking for a gratuity or complaining about the amount.
Nonetheless, both Americans and Germans were more likely to leave a tip than any of the six other countries surveyed, which included Russia, Brazil, France, Britain, Spain and Italy.
"Tipping is a cultural norm in the States, and U.S. travelers have a tendency to take their customs on the road, whether they are on American soil or traveling abroad," said TripAdvisor, the world's largest travel website, in a news release on Thursday.
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Among the countries surveyed, Italians seemed to be the least generous tippers, with fewer than one-quarter saying they always tip when on holiday.
—By CNBC's Katy Barnato