Bill Splitter
Split a bill instantly, or settle up who pays whom across multiple expenses (fewest transfers, weights) when some already paid.
About this tool
Real-life bill splitting is rarely just "divide the total by the number of people." Someone often covers several costs up front, the group changes from day to day, or you want to weight shares by how much each person consumed. The "Settle up" tab handles these cases and works out exactly who should pay whom. Everything is calculated in your browser; the amounts and names you enter are never sent to a server.
How settlement works (net balances)
Settlement is built on the idea of a net balance. For each member it computes "total paid β total they should owe." A positive balance means they receive money; a negative one means they pay. Because all balances always sum to zero, the total to receive and the total to pay match exactly. The only remaining question is how to cancel out those balances β and that is what the settlement modes decide.
When it helps
- A multi-night trip where lodging, transport, and drinks were each covered by a different person
- Different attendees each day β four people on day one, five on day two
- An organizer who booked and paid for everything and needs to collect afterward
- Charging non-drinkers less and heavy orderers more
- Some people already paid up front and you need to collect from the rest
You express these by logging each spend as an "expense (event)" and choosing who paid and who shares it. Because participants are chosen per expense, different headcounts per day just work.
Choosing among the four modes
The result (who pays whom) can be produced four ways. Switch depending on your goal.
- Pay each payer β the simplest: for each expense you pay your share directly to whoever covered it. Clear and traceable per item; mutual amounts are not offset, so transfers can go both ways.
- Fewest transfers β consolidates so the number of payments is minimized. Best for reducing the hassle of bank transfers.
- Fair to each payer β repays everyone who covered costs in proportion. More transfers, but every payer is reimbursed proportionally.
- Top-down settle β offsets balances in list order; easy to follow.
If in doubt: use "Fewest transfers" to minimize transfers, or "Pay each payer" to keep a clear link to each item.
Rounding amounts for easy transfers
Under "Round amounts" you can pick 100 / 1,000 / 10,000 yen so transfer amounts become multiples of that unit β handy when requesting bank transfers. The total is kept exact via the largest-remainder method, so rounding never creates or loses a single yen (the proportional mode also splits in unit steps).
Common gotchas
- Treating others works too: set the treater as the payer and leave them out of the participants, and they bear none of that cost.
- Weights are per expense: 0.5 for a non-drinker, 2 for someone who ordered a lot (default is 1 for everyone, i.e. an even split).
- One person can cover costs any number of times; specifying the payer on each expense sums them up.
- Your input is auto-saved on this device. To start over, use "Reset all" at the top of the Settle up tab.
How to use
- Enter the total amount and the number of people.
- Pick a rounding unit (Β₯1 / Β₯10 / Β₯100 / Β₯1000).
- See the per-person amount, total collected, and surplus.
FAQ
How is the remainder handled?
You choose from two ways. With the 1-yen unit, only as many people as needed pay one yen more so the collected total matches the check exactly. With rounding to a 100- or 1,000-yen unit, each person is lined up on a clean amount and the resulting difference is shown as a surplus.
What if participants change, like four people on day one and five on day two?
Use the "Settle up (who pays whom)" tab. Log each day as a separate expense and pick who shares it. Each person is only charged for the expenses they took part in, so different headcounts per day settle correctly.
What if some people paid up front and others have not paid yet?
Set who paid on each expense; the amount they covered is added to their balance. After totaling, the tool shows how much each member receives or pays, and a list of exactly who should hand how much to whom.
What is the difference between the settlement modes?
"Fewest transfers" minimizes the number of payments (someone receives or pays a consolidated amount). "Fair to each payer" repays each person who covered costs in proportion, so there are more transfers but it is fair. "Top-down settle" offsets balances in list order and is easy to follow. None leave anything over or short.
Can I set some people to pay more or less?
Yes. In the "Settle up" tab, turn on "Use split weights" to set a weight (multiplier) per participant on each expense β 0.5 for someone who did not drink, more for the organizer, and so on. Without weights, everyone splits evenly.
Is what I enter sent anywhere?
No. Everything is calculated in your browser, and amounts, headcounts, and member names are never sent to a server. Your input is stored only on this device so you can pick up where you left off.