{"version":"1.1.0","schema":"https://www.oneagentaday.com/api/schema.json","agent":{"title":"Trip Cost Splitter","slug":"trip-cost-splitter","date":"2026-10-18","issue":44,"category":"finance","categoryLabel":"Personal Finance","tags":["money","travel","splitting-bills","friends"],"difficulty":"easy","runtimes":["ChatGPT","Claude","Gemini"],"excerpt":"Paste the messy list of who paid for what on a group trip. Get who owes whom, settled in the fewest possible transfers.","problem":"The trip was great. Now there are 23 expenses in a group chat, two currencies, one person who skipped the dinner, and nobody wants to do the math.","videoUrl":null,"url":"https://www.oneagentaday.com/agents/trip-cost-splitter","apiUrl":"https://www.oneagentaday.com/api/agents/trip-cost-splitter.json","promptUrl":"https://www.oneagentaday.com/agents/trip-cost-splitter/prompt.txt","configUrl":null,"configFilename":null,"license":"CC-BY-4.0","howItWorks":"Splitting a trip sounds like a five-minute job until you open the group chat. Someone paid the Airbnb, someone else the car, one person missed a dinner, and somebody already sent money halfway through. Apps like Splitwise work if everyone logged things as they went. Usually nobody did.\n\nThis agent takes the mess as it is. You paste the list, in whatever shape it's in, and it works out who shared each cost, what everyone paid, what everyone owes, and then the fewest transfers that settle it.\n\n## What to paste\n\nEvery expense with the amount and who paid. Say who skipped what in plain words, like \"Tom wasn't at dinner.\" Add any money that already moved between people. If there's a second currency, give the exchange rate you all agree on, or it will ask.\n\n## What you get back\n\nA line-by-line table showing how each expense was split, so anyone can check their own part. Then a per-person summary: paid, owed, and the balance. Then the transfer list, written so you can paste it straight into the chat (\"Lea sends Mia 207.04\").\n\nIt shows the math and checks that the balances add up to zero. If a line is ambiguous, like \"dinner 212, Lea\" with no mention of who ate, it assumes everyone and says so, so you can correct it.","steps":[{"name":"Dump the expenses","text":"Scroll the group chat or your notes and paste every expense as-is: what, how much, who paid. Typos and mixed formats are fine. Write down who skipped what in plain words."},{"name":"Add the edge cases","text":"Mention any money that already changed hands, any second currency with the rate you want to use, and anyone who should pay a different share (like one room costing more)."},{"name":"Run the prompt","text":"New chat in ChatGPT, Claude, or Gemini. Paste the prompt, then your list. If it flags a line as unclear, answer the question instead of guessing."},{"name":"Check and send","text":"Look at the per-person table. If the totals look right, copy the transfer list straight into the group chat. Each person sees exactly one or two payments to make."}],"demo":[{"second":0,"label":"The mess","detail":"9 expenses from a Lisbon trip, one skipped dinner, one boat tour Jonas sat out, and 100 already sent."},{"second":8,"label":"Who shares what","detail":"Each cost gets the right people. Dinner splits 3 ways, the boat tour 3 ways, everything else 4."},{"second":16,"label":"Netting out","detail":"Paid minus owed per person. Mia is up 475.96. Lea owes 207.04, Tom 190.88, Jonas 78.04."},{"second":24,"label":"Settled","detail":"Three transfers, smallest possible. Totals check out to the cent."}],"sampleInput":"4 of us: Mia, Jonas, Lea, Tom. Lisbon, 3 nights.\n\nAirbnb 840 EUR - Mia paid, split 4 ways\nRental car 210 EUR - Jonas\nGas 96 - Jonas\nGroceries 64.50 - Tom\nDinner Friday 212 - Lea, Tom wasn't there\nBoat tour 180 - Mia, everyone except Jonas\nPastéis + coffee 18 - Tom\nParking 25 - Lea\nTom already sent Mia 100 on the second day\n","prompt":"You settle shared expenses after a group trip or event. You are careful with numbers and you show your work.\n\nINPUT\nA messy list of expenses: what it was, the amount, who paid, and notes about who shared it. It may include payments already made between people, more than one currency, and uneven shares.\n\nHOW TO WORK\n1. List the people. If a name appears that is not in the group, ask.\n2. For each expense, decide who shares it. Default to everyone unless the notes exclude someone. Uneven shares (a bigger room, someone drank and someone didn't) only if the notes say so.\n3. Convert every amount to one currency. Use the rate the user gave. If none is given, ask once, then stop.\n4. For each person: total paid, total owed, balance = paid - owed. Treat money already sent between people as a payment from the sender to the receiver.\n5. Check that all balances add up to zero (allow 0.01 per person for rounding). If not, find the error before answering.\n6. Find the fewest transfers that settle everyone: repeatedly match the person who owes the most with the person owed the most.\n\nRULES\n- Round to 2 decimals only at the end. Put any leftover cent on the person owed the most.\n- Never guess silently. If a line is unclear, make the most likely assumption and list it under Assumptions.\n- No advice about budgeting or apps. Just settle the money.\n- Plain language. No emojis.\n\nOUTPUT\n## Expenses\nA table: expense, amount, paid by, split between, share each.\n\n## Balances\nA table: person, paid, owed, balance (+ means they get money back).\n\n## Transfers\nA short list in the form \"Name sends Name amount\", ready to paste in a group chat.\n\n## Assumptions\nBullets. Each assumption you made, so the group can correct it. Write \"None\" if there were none.","config":null}}