- The tipping sweet spot at restaurants is 16 to 20 percent, CreditCards.com finds.
- Republican men who live in the Northeast and use a credit or debit card are the best tippers, the survey finds.
- Men tend to be more generous restaurant tippers than women, but women are better when it comes to hotel housekeeping, baristas and hair stylists.
- 20 percent is considered a "generous tip."
Only half of restaurant tippers fall within the gratuity sweet spot of 16 to 20 percent, according to a new report by CreditCards.com.
The study, a survey conducted last month, examined tipping behavior at restaurants, hotels, coffee shops and hair salons. It sampled 1,002 adults who used cash, credit or debit cards.
It found that the most generous tippers in the U.S. are Republican men who live in the Northeast and use a credit or debit card. They generally tip at a median of 20 percent when dining at a sit-down restaurant.
On the other hand, it said, women tip a median of 16 percent, while Democrats, Southerners and cash users tip a median of 15 percent.
"People now see 15 percent as a floor rather than a ceiling when it comes to tipping. The truth is that the median was about 18 percent. So, it's somewhere between 15 and 20," Matt Schulz, senior industry analyst at CreditCards.com, said Monday on CNBC's "Squawk Box."
"It's really all about income," Schulz said. "The more cash you have, the more likely you are to plunk a little more down at the table at the end of the night."
The survey found that 27 percent of hotel customers always tip their housekeeper, 29 percent who visit coffee shops always tip, and 67 percent always tip their hair stylist and barber.
Men tend to be more generous restaurant tippers than women, but women are better when it comes to hotel housekeeping, baristas and hair stylists.
"My general rule of thumb is if it is a business you are going to go to and you're going to spend time there, and a person you're going to see on a regular basis, when in doubt give a tip," Schulz said.
The report also found payment apps like Square prompt users to tip in scenarios where they might not otherwise. Ride-hailing services Uber and Lyft are part of a trend where it has gotten easier to tip, Schulz said.
A personal or emotional connection also might influence someone's tip.
"Everybody has been in a situation where they're rummaging through their pockets to find a couple of singles to tip somebody. And there has been certainly situations where you ended up not tipping somebody because you didn't have the cash," Schulz said.
The phone survey, which was conducted by Princeton Survey Research Associates International, had a margin of sampling error of plus or minus 3.7 percentage points.
CreditCards.com offers price comparisons for credit cards.