Lake Fong, Post-GazetteFrom left, Ashwin Bharambe, Amit Manjhi,and Shashank Pandit, 24, Ph.D. students at CMU and co-founders of Buxfer.
The stickiest math problems at Carnegie Mellon University aren't always found in class.
Sometimes they involve a student who does $15 of grocery shopping for a roommate, who reciprocates by putting $8 on a credit card for Chinese takeout and calling it even.
"It gets awkward," Carnegie Mellon junior Darian Ghorbi said.
Enter three doctoral students who have created a Web site, www.buxfer.com, so students can track their shared expenses and remind one another who owes what to whom.
The site, short for Bucks and Transfer, is intended to keep casual debts large and small from straining campus friendships. Like social networking sites Facebook and MySpace, it is attracting users from an age group that seems to all but live online.
It's also an age group that's prone to pooling expenses and borrowing small amounts from each other.
Buxfer has been up for seven weeks, yet it has 1,500 users in six countries and is tracking more than $500,000 worth of transactions, everything from lunch tabs to grocery bills to a car loan in India. About 25 percent of the users attend Carnegie Mellon.
Anyone with an e-mail address can log into the free, password-protected service, though students account for an estimated 90 percent of its users, said Shashank Pandit, 24, a Carnegie Mellon doctoral student in computer science from Bombay, India, and one of the site's creators.
No money actually changes hands on Buxfer. Users can log in and form groups with friends, roommates or office colleagues, anyone with whom they typically split bills.
When somebody logs a group payment, Buxfer can automatically divide up each members's share, then alert others in the group by e-mail that an expense involving them has been posted. Net balances can be updated by any member as debts are paid and new expenses are incurred.
A note on a refrigerator can easily get lost. Not so with a debt tracked on Buxfer.
"As long as you are online, you can get into your account from anywhere in the world," Mr. Pandit said.
Grace Soh, 23, a Carnegie Mellon graduate who lives in California, said she and her roommates use Buxfer to keep straight their shared household expenses.
Gaurav Veda, a Carnegie Mellon graduate student, said Buxfer was useful to him and seven close friends who regularly dine out together. Rather than divide up the check at the table, they often let one person pay and collect later.
Sometimes, the results weren't pretty.
"It was sort of getting out of hand. Someone would tell me, 'Oh, we went to dinner two months ago, and you still haven't paid me,' " said Mr. Veda, 22, a computer science student from New Delhi. "Sometimes they would owe me."
"It's a little strange to tell people, 'Oh, you owe me $10.' Its not a huge sum of money, but if it's five people who each owe you $10, then it matters," he said.
Buxfer has been an eye-opener for Mr. Veda because of how much money flows among him and his friends. The site is helping him track $300 in debts others owe him, as well as $1,500 he owes to a friend who bought an airline ticket to India for him.
Experts on personal finance say incidental spending, though often overlooked, can be a significant contributor to financial strain. How those seemingly small expenses add up is clear from a national survey this fall of full-time undergraduates at four-year colleges.
Students reported spending $751 a year just to eat out, according to the survey by Student Monitor, a market research firm in Ridgewood, N.J. Expenditures for movies, concerts and other entertainment reached $571 a year, the survey found.
Even the daily $3 trip to the coffee shop has long-term implications, said Mark Guimond, executive director of the Texas-based American Association of Debt Management Organizations. "Over 365 days, you've spent over $1,000 on coffee," he said.
On campus, Buxfer won't shame a deadbeat into paying up.
"You can't do much about those people anyway," Mr. Pandit said. "They would just look at the Web site and ignore it."
He said the more likely benefit is preventing misunderstandings about loans between well-intentioned friends. "Everyone is human. People forget," he said.
Mr. Pandit said he and fellow doctoral students from India, Amit Manjhi and Ashwin Bharambe, hatched the idea leading to Buxfer three years ago when they grew tired of keeping track of lunch tabs and other shared expenses. Initially, they created a debt-tracking software program for their own use but got so many requests from friends for copies of it they decided to develop a Web site.
The site bears some similarity to www.billmonk.com, a money-tracking site launched in January by a Seattle startup. But Buxfer's creators say their service offers a simpler approach to tracking debts within groups and allows individuals to monitor their own spending patterns.
Buxfer, launched Sept. 19, is not a slam dunk with everyone, even on a campus as tech-savvy as Carnegie Mellon.
"I would consider using this, but I also feel like it's kind of insulting," said Mr. Ghorbi, 20, a mechanical engineering major from Boston. "Like, I'm going to document every cent you owe me."
Even some regular users who give the site high marks have recommended improvements, some of which Buxfer is making.
Computer science professor Michael Shamos, who runs Carnegie Mellon's master's program in e-business technology, wondered if Buxfer, as currently designed, will hold user interest long term. It would be better, he said, if there were added features, such as a way to link to one's online banking account, to PayPal or to another site enabling actual payments.
"It begs for more," he said.
"I have to admit, there's something cool about it," he said of the site. "It's a boon for disorganized people. I happen to be one of those people. My life consists of little pieces of paper lying around the house."
Bill Schackner can be reached at email@example.com or 412-263-1977.