LumelaWho owes who calculator
List the IOUs in your group. The calculator nets them out and shows the fewest payments that clear every debt — free, private, no account.
- No sign-up
- Works offline
- Stays on your device
No debts yet — add the first one below.
How it works
- Add the peopleType a name for everyone involved — or leave the numbered placeholders.
- Enter each debtPick who owes, who they owe, and how much. Add the same pair twice or in both directions if that's what happened — it all nets out.
- Read the balances and transfersEach person's net position appears instantly, with the fewest payments that clear everything and how many debts they replace.
- Share itSend the link or copy the summary into the group chat. The data travels inside the link — nothing is stored on a server.
Example: four friends, five IOUs
Four friends come home from a trip with five loose IOUs between them — the kind that pile up when people cover for each other at the bar, the ticket office and the supermarket:
| Who owes | Owes to | Amount |
|---|---|---|
| Dana | Tom | $40.00 |
| Tom | Avi | $25.00 |
| Avi | Dana | $10.00 |
| Noa | Tom | $30.00 |
| Avi | Noa | $15.00 |
Add up what each person is owed and subtract what they owe, and every debt collapses into one net balance:
| Person | Is owed | Owes | Net |
|---|---|---|---|
| Dana | $10.00 | $40.00 | -$30.00 |
| Tom | $70.00 | $25.00 | +$45.00 |
| Avi | $25.00 | $25.00 | $0.00 |
| Noa | $15.00 | $30.00 | -$15.00 |
- Dana → Tom: $30.00
- Noa → Tom: $15.00
5 debts become 2 transfers. Avi ends up square — what they owed and what they were owed cancel out, so nothing moves through them. Got receipts instead of IOUs? Use the trip bill splitter.
Keeping score for a whole trip?
In Lumela everyone logs expenses from their own phone — split evenly, by exact amounts or by shares, with several payers, guests without an account, receipts and a rate frozen per currency. Balances update for the whole group, showing who owes who directly, and you record a settlement when someone pays. Works offline too.
Questions
How does the debt simplifier work?
Every debt is added to one person's balance and taken from the other's, so each person ends with a single net number. Whoever is negative pays whoever is positive, largest amounts first, until everyone is at zero. A group of n people never needs more than n − 1 transfers, and a loop — A owes B, B owes C, C owes A the same amount — needs none at all.
Is this the same as splitting a bill?
No. This tool starts from debts you already know ("I owe you 40"). If you have expenses and want to know who owes what, use the trip bill splitter — it works out the shares first and then the same fewest transfers.
Does the Lumela app simplify debts like this?
No — and on purpose. Lumela shows pairwise balances: who owes who directly, so every number traces back to real expenses, and you record a settlement when someone pays. When the group just wants the fewest payments at the end, run the balances through this calculator.
Can I use different currencies?
One calculation uses one currency — pick it above the debts, and changing it keeps the amounts. For a trip that spends in several currencies, the Lumela app records each expense in its own currency with the rate frozen on that expense.
Is it free, and where is my data stored?
Free, with no account and no limit on people or debts. Everything stays in this browser and keeps working offline once the page has loaded. A share link carries the debts inside the link itself — nothing is sent to Lumela or anyone else.
Guides on this
Who owes who: settling up after a trip without a spreadsheet
Who owes who what after a trip: simplified debts vs pairwise balances, why the "optimal" answer feels wrong, and a four-minute script for settling up.
How to split trip expenses without anyone feeling cheated
A practical system for splitting trip expenses with friends: what to log, how to split unevenly, multiple payers, and why trust beats the maths.
How Lumela Keeps Trip Expenses Fair — No Spreadsheet Needed
See who owes who on your group trip in real time. Lumela logs every shared expense and does the math automatically, so nobody has to chase anyone.