The research behind splitting bills
We read the academic papers on splitting bills and shared money so you don't have to. What actually holds up, and what it means for the next time you're staring at a check trying to work out who owes what.
Why the group always over-orders
A field experiment found people spend about a third more when the bill is split evenly. Why it happens, and when the even split is still fair.
The math behind “simplify debts”
Any group settles in at most n−1 payments. The true fewest transfers is NP-hard, and it never matters for a real dinner. Here's why.
One good default beats ten options
A fair-division site ships one algorithm per problem, on purpose. And people can feel the difference between a technically fair split and a good one.
You both remember paying more than half
In the classic study, 27 of 37 couples' combined claims of who does what added up past 100%. Neither of you is lying; the ledger in your head is just biased, and it gets worse as the group grows.
Why keeping score with friends feels gross
Five studies on why exact repayment between friends reads as petty, from the 1979 communal-exchange experiments to the $9.99 Venmo effect, and why the fix is letting a neutral ledger keep the score.
The small debt nobody agrees exists
Borrowers and lenders carry different memories of the same small loan, and neither one is lying. Five papers on why little IOUs between friends never get settled until someone writes them down.
The theorem that ends rent fights
A 1999 proof guarantees a rent split no roommate would trade, and 1,800 Swedish apartments show what “utilities included” really costs.
Dinner with friends is bigger before the bill even lands
Food diaries, a brewpub experiment, phone check-ins and 800,000 receipts: how the group inflates the bill before anyone picks a split rule. The split method is the only lever you control.
Why dvup wobbles: the case for a playful money app
The founder's case for wobbling bubbles and animal faces in a money app, from the ATM beauty studies to the Robinhood confetti line.
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Scan the receipt, share one link, and everyone pays their share. Free on iOS and Android.