Trip Cost Splitter

How to use the trip cost splitter

1. Under People, type the names of everyone on the trip. Add a person adds a line; × removes one (at least two people stay).
2. Optionally enter a Currency (optional) such as $, € or CAD. It only labels the amounts, so any currency works.
3. Under Expenses, fill one block per expense: a Description, who it was Paid by, the Amount, and under Split among tick the people who share it. Everyone is ticked by default; untick someone who didn’t take part, for example a person who skipped a dinner. Add an expense adds a block and × removes one.
4. Read the results as you type: the Total spent, the Average per person, the number of Transfers to settle, then Who pays whom and the Balances table with what each person Paid, their Share and their Balance.
5. Copy summary or Download .txt to share the result in a group chat or an email. Start over clears the list.

Your people and expenses are saved automatically in this browser (local storage), so you can close the page and add expenses later during the trip. Nothing is sent to a server.

How the balances are calculated

Each expense is divided equally among the people ticked for it, to the cent. When an amount doesn’t divide evenly, the leftover cents go to the first people in the split, so the shares always add up exactly to the amount (10.00 split three ways gives 3.34, 3.33 and 3.33).

• Share = the sum of that person’s parts of every expense
• Balance = paid − share. A positive balance means the group owes that person money; a negative one means they owe the group.

The balances always add up to zero: every amount someone paid for others is exactly what those others owe.

How the transfers are chosen

Instead of everyone paying back everyone for each expense, the tool settles the balances directly. It uses a greedy method: the person who owes the most pays the person who is owed the most, as much as possible; then it repeats with the new balances. This needs at most one transfer fewer than the number of people, and in everyday cases it gives the smallest number of transfers. For some unusual combinations a cleverer arrangement could save one transfer, but finding the true minimum is a hard problem and rarely worth it.

Example. Alex pays 90 for gas and Sam pays 120 for groceries, both shared by all three. Jordan pays 45 for museum tickets for Alex and Jordan only. The total is 255. Alex’s share is 30 + 40 + 22.50 = 92.50, so Alex’s balance is −2.50; Sam’s is 120 − 70 = +50.00; Jordan’s is 45 − 92.50 = −47.50. Two transfers settle everything: Jordan pays Sam 47.50 and Alex pays Sam 2.50.