Although most UK customers are happy to leave a tip when dining out, a new survey reveals that between 6% and 10% of the bill is often considered adequate.
In a survey of 1,008 customers by internet bank Smile, a large minority of 29% said that they would not pay more than 5%, and 4% of diners left nothing at all.
The study found that more customers would like to refrain from tipping, but lacked the nerve to do so.
More than half left tips because it was "the done thing", 11% did not want to look mean, 10% felt sorry for the restaurant staff, and 10% didn't want to cause a fuss.
One in five of those questioned said they felt pressurised into leaving a gratuity for waiters even if the food or service was not up to scratch. The report estimated that diners paid out £328m a year in tips which they felt were undeserved.
Youngsters were more likely than older people to cave in under the social pressure. More than a quarter of 16- to 24-year-olds said they felt obliged to tip, but only 14% of over-65s would pay up if they thought it was unmerited.
The most niggardly diners were found in the North-east, where only 58% of restaurant customers left any money.
According to the study, a tip of 10% was considered the norm in the UK and Europe, rising to 15% for good service and 20% for an outstanding experience.
"We haven't quite reached the US situation where tipping is part of the culture, so people are unclear about who to tip and how much," said Phil Garlick, director of operations at Smile.
"This means that people are happy to pay extra for good service. But when they don't get it, they panic and tip anyway."