On a trip across borders, money moves in several currencies at once. Nobody wants to stop at every dinner to convert. The easy way is to keep a record as you go and leave the maths for the end. To do that fairly, agree two things before you start.
Which exchange rate to use
There’s no single “correct” rate. What matters is that the group picks one approach and sticks to it. These are the three common choices.
The rate on the day
Convert each expense at the market rate on the day it was paid. It’s the most precise, but someone has to look up a rate for every expense.
One rate for the whole trip
Agree one rate per currency, for example the rate on the day you settle up. Simple, and for a short trip the difference is usually small.
What the card actually charged
Use the amount on the payer’s bank or card statement. It covers exactly what they lost, fees included, but statements arrive later and every card uses a different rate.
For most friend trips, one agreed rate is the least work and the fewest arguments. If one person paid for something big, like the hotel, and their card charged a noticeably different amount, it’s fair to use their statement figure for that one expense so they aren’t out of pocket.
Worked example: three friends, three currencies
Aisha lives in Dubai, Ben in the US and Chiara in Italy. They spend a week together in Dubai and Rome and agree to split everything equally. Each person pays for one big thing, in the currency it was priced in.
| Who paid | For | Amount | In USD |
|---|---|---|---|
| Aisha | Hotel, Dubai | AED 1,101 | $300 |
| Ben | Desert safari | $450 | $450 |
| Chiara | Apartment, Rome | €600 | $660 |
| Total | $1,410 |
Example rates for easy maths: 1 USD = 3.67 AED (the dirham is pegged at about 3.6725) and 1 EUR = 1.10 USD. Use your own agreed rates.
Option 1: convert everything and settle in one currency
The trip cost $1,410, so each person’s share is $470. Each balance is what they paid minus their share.
| Person | Paid | Share | Balance |
|---|---|---|---|
| Aisha | $300 | $470 | owes $170 |
| Ben | $450 | $470 | owes $20 |
| Chiara | $660 | $470 | is owed $190 |
Two payments settle the whole trip: Aisha pays Chiara $170 and Ben pays Chiara $20. Chiara receives $190, which is exactly what she was owed.
The catch is the rate. If the euro had been at 1.08 instead of 1.10, the apartment would count as $648, and everyone’s numbers would shift a little. That’s why agreeing the rate first matters.
Option 2: settle each currency separately
You can skip conversion completely. Split each expense in its own currency, and settle each currency on its own.
| Person | AED | USD | EUR |
|---|---|---|---|
| Aisha | +734 | −150 | −200 |
| Ben | −367 | +300 | −200 |
| Chiara | −367 | −150 | +400 |
That takes six payments: Ben and Chiara each pay Aisha AED 367, Aisha and Chiara each pay Ben $150, and Aisha and Ben each pay Chiara €200. Nobody has to agree a rate, and it works well when people hold the currencies already, such as Aisha paying in dirhams from her UAE account. It’s more transfers, though.
Both options are fair. Converting is fewer payments with a rate to agree. Per currency is more payments with nothing to argue about.
Tips that prevent arguments
- Record the currency you actually paid in. Log the AED 1,101, not your own guess at its dollar value. You can always convert later; you can’t un-round a guess.
- Agree the rule before the trip. One rate or rate on the day, one currency or several. A message in the group chat is enough.
- Note card fees. If your card added a foreign transaction fee, write it in the expense note. Decide upfront whether fees are shared or belong to the person who chose the card.
- Pay in local currency at the card machine. When a terminal offers to charge you in your home currency, the conversion it offers often includes a markup. Paying in the local currency is usually the better deal.
- Write down cash exchange rates. If you change cash at a counter, note the rate you got, so cash spending can be converted the same way.
- Round only at the end. Keep exact amounts while you log; round the final payments.
How Duesy handles it
In Duesy, each expense keeps the currency it was entered in. Balances and the “fewer payments” plan are worked out separately for each currency, so the app never applies a rate nobody agreed to. For the trip above it would show the per-currency payments from option 2, and settle-up payments are recorded in the currency of the debt.
With Duesy Pro, or a Trip Pass on the group ($2.99 for one group for 30 days), Duesy also shows amounts converted into your own currency using daily exchange rates. Converted figures are marked with “≈” and the original amount stays visible. They’re a guide for reading; they don’t change what anyone owes.
If you’d like to try it, make a trip group before you leave and let whoever pays log the expense in whatever currency it was. More on the basics in splitting bills on a trip, or try the trip cost splitter for a quick one-off.
Questions
What exchange rate should we use to split trip costs?
Any rate the group agrees on before the trip. One rate per currency for the whole trip is the simplest. The rate on the day of each expense is the most precise. The payer’s card statement is fairest for a single big expense, because it shows what they actually lost.
Should we settle in one currency or in each currency?
Settling in one currency means fewer payments but needs an agreed rate. Settling each currency separately needs no rate but takes more transfers. In the three-friend example, one currency took two payments and per currency took six.
Who pays the foreign transaction fee?
Agree it before the trip. Some groups treat card fees as a shared trip cost; others leave them with the person who chose that card. Either way, note the fee on the expense so everyone can see it.
Should I record an expense in the local currency or my home currency?
Record it in the currency you actually paid in. That keeps the record exact, and you can convert at the agreed rate when you settle up.
Does Duesy convert currencies automatically?
Each expense stays in its own currency, and balances and settle-up are worked out per currency. With Pro, or a Trip Pass on the group, Duesy also shows an approximate converted total in your currency, marked “≈”, using daily rates. The conversion is for reading and doesn’t change what anyone owes.