Get behind a shopper who has a full cart
That may seem counterintuitive, but data tell a different story, said Dan Meyer, a former high school math teacher who is the chief academic officer at Desmos, where he explores the future of math, technology and learning.
"Every person requires a fixed amount of time to say hello, pay, say goodbye and clear out of the lane," he said in an email.
His research found all of that takes an average of 41 seconds per person and items to be rung up take about three seconds each.
That means getting in line with numerous people who have fewer things can be a poor choice.
Think of it this way: One person with 100 items to be rung up will take an average of almost six minutes to process. If you get in a line with four people who each have 20 items, it will take an average of nearly seven minutes.
Those minutes add up. Richard Larson, a Massachusetts Institute of Technology professor who is considered the foremost expert on queues, estimated that Americans spend 37 billion hours a year waiting in lines.
Go left for faster service
Robert Samuel, founder of Same Ole Line Dudes, a New York-based service that will stand in line for you, said in an email that most people are right-handed and tend to veer to the right.
Look for female cashiers
"This may seem sexist, but I prefer female cashiers," Samuel wrote. "In my experience they seem to be the most expedient at register transactions and processing."
A. J. Marsden, an assistant professor of human services and psychology at Beacon College in Leesburg, suggested checking to see if a cashier was talkative and commenting on every item being scanned. If so, avoid this line "unless there is no one in that line, in which case, just deal with the chatty cashier," she said in an email.
Study the customers ahead and what they are buying
It is not just the number of people ahead of you, but their age and what they are buying that can make a difference, Marsden said. Older people will take a bit longer because they can have difficulties that delay the checkout process, such as not understanding how a debit card works, she said.
Also consider the number of different items they are buying, Larson said. Six bottles of the same soda will go faster than six totally different items, some of which cannot be scanned, such as vegetables, he said.
If you have no irregular items, such as produce, use a self-service checkout, Meyer said. "You'll lose the human contact but gain time," he said.
Choose a single line that leads to several cashiers
Not all lines are structured this way, but research has largely shown that this approach, known as a serpentine line, is the fastest. The person at the head of the line goes to the first available window in a system often seen at airports or banks.
Getting into a single line also provides a sense of psychological relief because it eliminates the choice of where to go and second-guessing about the best line to choose, said Julie Niederhoff, an assistant professor of supply chain management at Syracuse University.
Still, most people prefer to take their chances with parallel lines — individual lines dedicated to a single cashier — even though most of the time they end up picking a slower line, Marsden said.
What can you do to speed up service?
• Always face bar codes toward the cashier.
• When buying clothes, remove the hangers and pull the tags out for easy scanning.
• Use the buddy system at the express lanes. Split the items so you each stay within the maximum number allowed and then get out the door quicker.
Remember: A lot of the waiting game is mental
To some degree, waiting is all in your head. Research has found that, on average, people overestimated how long they waited in a line by 36 percent.
Customers are more concerned with how long a line is than how fast it moves, according to research by professor Ziv Carmon of the business school Insead and professor Daniel Kahneman of Princeton University. Given a choice between a slow-moving short line and a fast-moving long one, people will often opt for the short line, even if the waits are identical.