How to split expenses in different currencies

To split expenses in different currencies, you need to agree one thing: a single currency for the group. Every expense — pounds in Edinburgh, dollars for a tour booked online, cash from an ATM — gets converted into it, and every balance and every final transfer is in that one currency. Everything below is about doing the conversion so that nobody quietly loses money on it.

Pick one group currency first

Choose the currency the group will settle in, which is almost always the one most people have in their bank account at home. A group of friends from Berlin and Madrid visiting Scotland should keep their books in euros, not pounds, even though most of the spending happens in pounds. The pounds are what things cost; the euros are what people actually lost.

Two rules follow from that:

• Each expense is entered in the currency it was paid in, then converted. Don’t convert in your head at the table and write down a guessed euro amount.
• Each person’s balance is only ever in the group currency. “I owe you €40 and £12” is not a balance, it’s an argument waiting for an exchange rate.

Which exchange rate to use when splitting

There are two candidates, and they are never quite the same:

• The rate of the day — the mid-market or central-bank rate you see in a currency app. It’s the same for everyone and easy to look up.
• The rate the bank actually charged — what appears on the payer’s statement once the payment clears. It includes the bank’s margin and, often, a card fee.

The fair one is the second. The payer didn’t lose “£420 at the official rate”; they lost whatever their bank took from their account. If you use the mid rate, the payer absorbs the bank’s margin on everyone’s behalf, and the person who put the most on their card loses the most.

In practice, use the rate of the day as a placeholder when you add the expense, and correct it when the payment shows up on the statement, usually a day or two later. kisir fills in today’s rate when you add an expense in another currency, and you can change it to what your bank charged.

A sense of scale: on a £420 hotel, the difference between a mid rate of 1.1700 and a charged rate of 1.1850 is €6.30. Not much on its own. Over a week of one person paying for the group, it can be €40–50 that one person has quietly given away.

Card fees and foreign transaction charges

Some cards add a foreign transaction fee on top of the rate; some don’t; some add one only at weekends. Either way, if the purchase was for the group, the fee is a group cost.

Two clean ways to handle it:

• Fold it into the rate. Divide the total that left the payer’s account, fee included, by the foreign amount. That is the effective rate; enter it, and the fee is spread over everyone who shared the expense.
• Enter it as its own small expense, split between the same people. Useful when the bank charges fees separately at the end of the month.

What you shouldn’t do is let the person with the “bad” card silently eat every fee because they were the one who paid.

Cash withdrawals

Taking £200 out of an ATM is not an expense. It’s moving your own money from one pocket to another. If you record the withdrawal as a shared cost, and then the dinner you paid with that cash too, the group will owe you twice.

Record what the cash was spent on, at the rate you got for that cash. The withdrawal itself tells you that rate: if £200 cost you €240.00 including the ATM fee, your cash rate is 1.2000, and a £96 dinner paid from that cash is €115.20.

Leftover cash at the end of the trip is yours, not the group’s — unless it came out of a shared kitty, in which case split it back to the people who put money into the kitty.

Show both figures

Every converted expense should show the original amount and the converted one side by side: £420.00 → €497.70. That way anyone can check the rate against their own app, and nobody has to take the conversion on trust. A ledger that shows only euro amounts invites the question “where did that number come from?” — usually on the last night. In kisir the ledger shows both.

A worked example in three currencies

Ana, Leo and Mia spend a long weekend in Edinburgh. The group currency is euros. Three expenses, each shared equally by all three:

Where the rates come from:

• Ana’s hotel: her statement shows €497.70 for £420. That’s 1.1850 — above the mid rate of 1.1700 that day, because her bank adds a margin. Converting at the mid rate would have shown €491.40 and cost her €6.30.
• Leo’s dinner: he took out £200 in cash and his bank charged €240.00 for it, fee included. That makes his cash rate 1.2000.
• Mia’s tour: booked on a US website in dollars; her card charged €139.50 for $150.

Each person’s share is €250.80, and each expense divides by three to the cent. Now the balances — what each person paid minus their share:

They add up to zero, as they must. Two transfers settle the weekend:

Ana receives €246.90, exactly what she paid beyond her own share.

Settle in one currency

Once everything is in the group currency, settling works the same way as any other trip: net everyone’s balance, then make the fewest transfers that clear it. The method is in settling up in the fewest transfers.

Two traps at the end:

• Don’t settle in leftover foreign cash. Leo handing Ana £40 in notes sounds tidy, but now someone has to convert it again, at a different rate, and the books stop adding up.
• Don’t settle at a different rate from the one you split at. If a payback must cross currencies — someone in the group really only has pounds — convert the final euro figure at the rate on the day of the transfer, and record the payment in euros.

When people have different home currencies

A group with one person paid in pounds and four in euros still uses one group currency. The person in pounds converts at their own bank’s rate when they pay for something, the same as anyone else, and settles in euros at the end — their bank does the last conversion. What doesn’t work is two parallel ledgers, one per currency, that nobody can add together.

For the rest of the trip — what counts as shared, uneven rooms, people arriving late — see how to split costs on a group trip.