How to split trip costs when you spend in different currencies
Convert each expense once, into one settlement currency, using the rate that matches how it was actually paid: the amount the card really charged, your own average rate for cash you changed, and only if neither is known, the day’s market rate. Then split and settle in that one currency.
The short method
- Pick one settlement currency for the group, for example USD.
- Record every expense in the currency it was paid in. Do not convert it in your head.
- Convert each expense once, using the right rate for how it was paid (below).
- Split the converted amount between the people who shared it.
- Add up what each person paid and what they owe, then work out a short list of transfers.
Which rate for which payment
- Card payment: use the amount your card statement actually charged, in your settlement currency. It already contains the bank’s rate and any fee. Until the statement arrives, use the day’s market rate and treat the figure as an estimate.
- Cash you changed: use your own average rate: the total you handed over divided by the total of foreign currency you got back, across all your exchanges. It is what the cash really cost you.
- Already in the settlement currency: no conversion at all.
- Neither known: fall back to the day’s market rate and mark the expense as estimated.
A worked example
Four friends spend a weekend in Lisbon and settle in USD.
Dinner, €86.40, paid by card. The statement later shows a charge of $94.18. That is the amount used. No exchange rate is needed.
Taxi, €40.00, paid in cash. The payer changed $200 into €180 before the trip, so their average rate is 200 ÷ 180 = 1.1111 USD per euro. The taxi costs 40 × 1.1111 = $44.44.
Museum tickets, €60.00, card statement not in yet. The day’s market rate is 1.09, so the expense is 60 × 1.09 = $65.40, marked as estimated until the real charge replaces it.
Now split the dinner four ways. $94.18 is 9,418 cents, and 9,418 ÷ 4 is 2,354 with 2 cents left over. Nobody can pay half a cent, so the two leftover cents go one each to the first two people: $23.55, $23.55, $23.54, $23.54. The shares add up to exactly $94.18, every time.
Three mistakes that make the numbers drift
- One fixed rate for the whole trip. Easy, but it ignores what the card and the cash actually cost.
- Converting each share separately. Rounding each share on its own loses or invents cents. Convert the whole expense first, then split.
- Using floating-point arithmetic. In a spreadsheet, keep amounts in whole cents, or round after every conversion, so totals match.
How Trip Split does this
Every expense keeps its original currency and how it was paid. For a foreign card payment you can enter what the card actually charged. For cash, you record the money you changed and Trip Split uses your own average rate. Only when neither is known does it use the daily rate, and it marks that expense as estimated. Amounts are kept in whole cents, and leftover cents are handed out one by one, so the shares always add up. At the end you get one number per person and a short list of transfers. See also how to split a trip when someone pays cash and the comparison with Splitwise and Tricount.
Common questions
Should I use one exchange rate for the whole trip?
No. Rates move from day to day, and card payments and cash are converted at different rates in real life. Converting each expense once, at the rate that matches how it was paid, keeps the result fair.
Do I convert each person’s share, or the whole expense?
Convert the whole expense once, then split it. Converting every share separately rounds each one on its own and the cents stop adding up.
What if the card statement has not arrived yet?
Use the day’s market rate as an estimate, mark the expense as estimated, and replace it with the real charged amount when it appears on the statement.
Which currency should the group settle in?
Pick the one most people want to send and receive, usually the home currency of the group. Everything is converted into it, so everyone ends up with one number.
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