[Courtney Knapp]

As one of the more mathematically inclined in my social circle (read: I've taken a math class in the last decade) I am often the person left figuring out how to divide the bill and determine the appropriate amount to tip.

At a restaurant this is an easy task--it is common practice to add somewhere between 15 and 20 percent. Here are a few special situations:

Q. How should I tip if the service was great but the food was bad?
A. Did you send your food back? You should have, that sends a message to the kitchen. Base your tip on the service and leave between 15 and 25 percent.

Q. How should I tip if the service was bad but my food was great?
A. Tip on the low end of the 15 and 25 percent range. Managers do notice low tips, if they see servers with consistently high tip averages or a server with low tips, they see patterns. If the service was so terrible that you're fuming, speak directly to a manager about the problem.

Q. Imagine the following situation: You are at lunch with four other people in a restaurant where the 18% service charges kicks in for tables of six or more. Halfway through lunch one of your dining companions announces she is pregnant. Assuming you are pro-life, how do you tip?
A. You are a smart ass. The automatic gratuity is at the discretion of the management, and isn't necessarily always enforced. However, it's generally common practice to only count those amongst the qualifying diners those who are in possession or have access to their own birth certificate.

At bars, tipping can be trickier. There seems to two schools of thought--those who tip on the amount of the bill (say 20%) and those who tip a certain amount on each drink (say $1).

After much debate, I use the following as my rule of thumb: One dollar per drink or 20% of the amount, whichever is higher.
A $5 pint? That's a dollar. But a $15 cocktail? That's $3.
(Depending on the service, the amount I tip might be much higher but rarely will it be less).
 
Here are a few special situations:

Q. How much should you tip when a bartender picks up one of your drinks? I ordered three $10 cocktails, when my bill arrived it was $20. How do I tip?
A. This depends on why the drink was free. Was there something wrong with your drink or did it take longer than usual? If so, base your tip on the $20 bill and don't add anything extra (after all, he's trying to correct a situation, and you are by no means obligated to tip him extra).
But there are other reasons a bartender might give you a free drink. He or she could be trying to get repeat business, or maybe you're a regular customer who brought a few friends with you this time and the bartender wants to show you he's grateful for the business. Free drinks are one of the ways your bartender can say "Thank you," and a bartender who gives you a free drink wants you to accept the gift, not just redirect the money you would have paid into his pocket.
In this situation, my personal rule is to tip on the original price, plus at least half the cash value of drink that was free. In the above case, I end up paying $31 instead of $36, saving money and expressing my gratitude.

Q. How much should I tip when your drinks are picked up by someone else? Imagine that you've had the same three $10 cocktails, and when you ask for the bill your bartender says your drinks have been picked up by a friend or a flirty stranger. A. This is your lucky day; you are in no way obligated to tip your bartender. It's nice if you decide to leave a few bucks and your bartender will certainly appreciate it, but you just got out of jail free!

Any disagreements? How do you feel about my rule of thumb? I am interested in feedback but ready to move on to a new topic, so feel free to e-mail me at MSCourt AT gmail DOT com.

In order to solve the age old mysteries of tipping, I enlisted the help of a few of my favorite restaurant industry friends: Jacob Grier a Portland based mixologist, writer, and brand ambassador; Derek Brown, an Atlantic contributor and an internationally recognized beverage expert; Gina Chersevani, a RAMMY Award winning mixologist from Ps7 restaurant; James Lindahl of EatBar; and Ron Dollete proprietor of both Lush Angeles and Sauce Supreme.