Restaurant and bar insiders shared their thoughts on tipping with us, including how much to leave and why. (Photo by Bill O'Leary/The Washington Post)

What is it about tipping that makes the process so fraught? Whether it’s confusion about what’s appropriate, guilt that you might not be leaving enough cash or just fuzzy math, there’s no part of the dining experience that creates more debate.

Making matters even more complicated, the rules change depending on where you go and what you order. How much should you tip at a fast-casual spot? And what happens when you get comped a drink?

We talked to restaurant and bar insiders to get their perspectives on how to handle a variety of situations. Most of them suggested taking a generous approach — that didn’t come as a surprise, considering they might be benefiting from the extra money. So we pressed for more than just guidelines. We wanted explanations. That way, the next time you’re signing the check, you’ll know what’s on the other side of the tipping debate.

When you're dining at a full-service restaurant

Tip 20 percent of your full bill.

That 15 percent standard? Forget it. Most diners are tipping above that figure — and for good reason. Just look at the numbers: Waiters in the District make an average of $27,360 a year, according to a report issued last year by the Bureau of Labor Statistics. Anyone who’s paid rent in this city knows it takes a lot more than that to live comfortably here.

Post food critic Tom Sietsema has weighed in on the issue in his weekly chat: “20 percent is the accepted standard right now, unless the service is not up to snuff,” he wrote, later adding that he arrived at that number based on his examination of “different financial/etiquette/consumer sites online and also years of experience in the industry. In 2016, a gratuity of 15 percent of the bill tends to reward ‘average’ service and is considered a decent starting point for tipping.”

Plus, from a diner’s standpoint, “it’s way easier to do the 20 percent math,” said restaurateur Jackie Greenbaum, who said she often goes up to 25 or 30 percent.

A variety of beans from around the globe are roasted, brewed and sold at Vigilante Coffee in Hyattsville. (Photo by Amanda Voisard/For the Washington Post)

When you grab a cup of coffee

Round up or add a dollar if you’re a regular or ordered a complicated drink.

Customers tend to round up to the nearest dollar or so when they do tip, said Chris Vigilante, founder of Vigilante Coffee Co. That happens more often when they become regulars and get to know their baristas.

David Guas, owner of Bayou Bakery in Arlington and on Capitol Hill, agreed. Sometimes all a barista does is turn around and pour a cup of coffee. But if you’re ordering a drink that takes more time and skill, such as an espresso-based latte or cappuccino, then a buck is reasonable, he said.

When you have lunch at a food truck

Drop a few dollars into the tip jar, but a little less than you would at a dine-­in spot.

Food truck workers aren’t just handing you food, said Najiba Hlemi, executive director of the DMV Food Truck Association. They’re often also prepping in the morning, cooking during lunch and washing down the truck after service.

Still, employees aren’t relying on tips like some restaurant servers are, so tips are appreciated but not expected, Big Cheese truck owner Patrick Rathbone said. He usually leaves a gratuity after he’s gotten his food, basing his decision on the service.

Brian Witthun (left to right facing), Nick Fasciano, Kate Lonergan and Caitlin Dimino and other patrons enjoy sandwiches at Taylor Gourmet. (Photo by Evy Mages for the Washington Post)

When you pick up something at a fast-casual eatery

A dollar or so is reasonable if the service was good.

For a time, Taylor Gourmet got rid of its tip jars, but the sandwich chain brought them back, partially because customers were asking to leave a tip, co-founder Casey Patten said. (Plenty of fast-casual eateries don’t have them.) The average tip is probably a dollar, he said, which equates to about 8 percent overall.

Tips tend to add up when service is fast, efficient and friendly, Patten said. You shouldn’t feel obligated to leave one, but if the staff is on their game and “someone wants to leave a little something extra, great for them for recognizing it.”

As with a food truck, it’s acceptable to drop the tip in after you’ve received your food.

When you're comped a drink or dish

Tip as you would on the full price.

The value of what you’ve been given hasn’t changed, even if you’re not paying for it. Steve Uhr, director of mid-Atlantic operations for the restaurant group that includes Tico and the Riggsby, said it’s understandable if people forget to tip on something they got free. “You’ve already consumed it. It’s not on the check to remind you,” he said. You won’t be ostracized for forgetting, but it’s a nice way to say thanks.

When you use a gift card

Tip on the total value of the meal, not just what you paid out of pocket.

Your waiter isn’t doing less work because someone else helped pay for your meal. You’re tipping for the service you’ve been rendered.

A bartender serves a beer at the Sovereign in Georgetown. (Photo by Dixie D. Vereen/For The Washington Post)

When you're drinking pricey craft beer instead of run-of-the-mill domestics

Tip a little extra.

There’s no question that you’d tip more for a porterhouse steak than for a hamburger. But some customers think there’s no difference between tipping $2 for two $4 bottles of Miller Lite, and tipping $2 for two $12 snifters of Belgian strong ale.

“I understand we’re only turning around and handing you a beer,” said Jack McAuliffe, a bartender at the Sovereign. “But I think that the service you’re getting, and the time and thought we’re putting into our beer program, is something that you can’t get anywhere else. We put in a lot of work to get to know these beers, and be able to help people” find the right choice on the menu.

When you order carryout from a restaurant

Consider a 10 to 15 percent tip, or at least a few dollars.

You may not be getting the full dine-in service, but someone has taken your order, packed up the bag and handed it off to you. Greenbaum said she at least rounds up a few bucks on carryout. “A service is being provided,” she said. “I’m not saying it should be much.”

Ted Passante, assistant general manager at the Lost Dog Cafe in North Arlington, said people often drop at least a dollar or two into the jar by the cashier when they pick up an order.

When you order delivery

Similar to takeout, 10 to 15  percent, or a few bucks.

The Emily Post Institute suggests 10 to 15 percent of the bill or $2 to $5 for pizza delivery, depending on the size of the order and difficulty of delivery. “I think delivery people should be tipped more,” Lost Dog’s Passante said. After all, they’re bringing food directly to your door.

When an owner serves you

Tip as you would a waiter.

Don’t overthink it. If an owner serves you, they’re your server. Just because they’re running the place doesn’t mean they haven’t earned a gratuity.

Mamadou Fall, co-owner of Chez Dior in Hyattsville, often works the dining room. He notices diners typically tip him less than his servers, even though, as he points out, he’s still providing the same service — or in some cases more, since he tends to spend extra time with tables explaining the menu.

Some restaurants have a tip pool, in which gratuities are collected and then distributed by position and hours worked. So if you aren’t tipping the owner, it might be costing the rest of the staff.

More restaurants nationwide are eliminating gratuities to pay staff higher wages. A D.C. restaurant has found that switching to a non-tipped pay structure has created a better business model and reduced tension between cooks and servers. (Daron Taylor,Jayne Orenstein/The Washington Post)

When you're drinking only water at the bar

Tip as if you were drinking booze.

Not everyone sitting at the bar wants to drink alcohol — or a non-boozy drink, for that matter. When Trevor Frye, who’s opening Marble Alley in Adams Morgan next year, took a month off drinking, he’d order a soda water with bitters, or another nonalcoholic drink. “I might not get a check for a soda and bitters, but I’d tip like every round I’d have was a full drink,” he said. “I’m sitting in a space where someone else could be sitting and drinking a $10 cocktail.”

He didn’t want the bartender to lose money just because he was drinking water, so he’d usually tip about $2.

When you're calculating a tip based on the pre- or post-tax amount

Calculate your tip based on the full bill.

Uhr said most diners base their tip on the post-tax total. Why? The answer goes back to our feelings about arithmetic: “I think it’s less math, honestly,” he said.

Greenbaum added: “I feel like generosity is always the right thing to do.”

Customers fill the Urban Farmhouse Tap Room at 3 Stars Brewing in Washington. (Photo by Friz Hahn/The Washington Post)

When you get a flight of tasting samples or a growler filled at a brewery

Toss a buck or two into the tip jar for samples. Tip 15 percent for takeout.

At some breweries, like the District’s 3 Stars, visitors receive tickets for sample tasters, so there’s no cash transaction to tip on. In that case, toss a dollar or two into the tip jar as a way to thank the person who poured your beer. Tip more if they offered helpful tasting notes.

When purchasing a growler or something else to go, think of it as any other carryout service, and tip around 15 percent for the person who’s rinsing your growler and making sure it’s filled with the correct beer.

“Obviously, like a bar, it’s based on service and knowledge about your product,” said Lyn Holland of 3 Stars. “If your bartender or brewery employee is answering a lot of questions to the best of their knowledge, definitely 15. More than 15 percent is obviously welcome, but not expected.”

It should go without saying, but if you’re hanging out in a brewery’s tap room on a Saturday afternoon and ordering pints while waiting for growlers, tip as you would as if you were at a bar.

When you've run a tab with the same bartender all night

Tip 20 percent, but maybe throw in a few more bucks.

From a bartender’s perspective, there’s a difference between a group hanging out for hours at one end of the bar and a couple at a high table that orders two glasses of wine and leaves. “There’s a direct relationship between the amount of time and service a group requires” and the amount they tip, said Brian Harrison, a bartender at Jackpot and Lost and Found.

If a crowd is making a lot of demands for drinks and shots, it might cause the bartender to focus less on other customers, and in that case, “maybe you could, or should, tip a little above” the usual amount.

When you order drinks at happy hour

Tip as you would if the drinks were full price.

“Happy hour is tough,” Frye said. “Let’s say that you have an $8 beer that’s $5 at happy hour. Every time someone orders one, you lose 20 percent of that $3. When you’re serving 100 or so people, that really adds up. And it’s not like you’re serving a different product or providing a different level of service.”

Volume alone doesn’t make up the difference: “Go out to your favorite bar on a Thursday, Friday or Saturday night, and it’s busier than it is at happy hour.” Frye’s general rule is to tip on 20 percent of what the original price would be, if you know it. (If not, tip higher than 20 percent of the happy hour price.)

Not all bartenders agree. (Some, in fact, don’t care.) But the bottom line is this: For a bar-goer, the difference between tipping on the happy hour price and the regular price means a buck or two. For a bartender, that can really add up.

When you're paying for drinks as you go vs. paying at the end of the night

It depends on a few things.

Usually, if you’re tipping a buck each time you order a beer, you’re tipping less than the bargoer who runs a tab and tips 20 percent at the end. Still, both approaches are considered fair.

“If you’re just coming up to the bar and getting a drink and walking away to stand on the other side of the room, then leaving $1 is acceptable,” McAuliffe said. “If you’re sitting at the bar for 20 or 30 minutes, and getting water,” and asking bartenders for help choosing a beer, “it should be 20 percent,” he said.

The rules change when it comes to tipping as you go for a well-made cocktail. Frye thinks $2 is the new norm in that case; $1 on a $12 cocktail is barely 8 percent. “It can be difficult,” he said. With cash, “there’s not an easy way to tip on a $12 cocktail,” which is $13.20 after tax in Washington.

Read more:

The do’s and don’ts of drinking at a bar

The unwritten rules of dining that all people should follow

The forgotten D.C. area restaurants that all diners should try