Who should pay for what on a group trip?

It does not matter who pays, as long as it is written down. Usually whoever books something pays for it — the hotel by whoever booked it, the car by whoever rented it — and day-to-day things go on whichever card is closest to hand.

How do you split costs when not everyone joins in?

Each expense is split only between the people who used it. If three out of five go on a day trip, that day trip is divided by three. A common pot split equally sounds simpler, but it is what ends up causing the argument.

What if something is paid in another currency?

Log it in the currency it was paid in and convert at that day’s rate for the total. Converting by eye, or using another day’s rate, is the most common source of error on longer trips.

Do you need an app to split trip expenses?

No, a shared note works. What you need is for everyone to log things in the same place, at the time: the problem is never the arithmetic, it is remembering three weeks later.

How to split expenses on a group trip

Log every expense with who paid, as it happens — not at the end. Then settling up is just subtraction: whoever put in more gets paid back, whoever put in less pays, and nobody has to bring it up.

The arithmetic was never the problem

Nobody falls out over dividing 240 by four. They fall out because, three weeks later, one person says they filled the tank twice, another cannot remember whether they paid for the second night’s dinner, and nobody knows what the trip actually cost. The money gets lost in memory, not in maths.

So everything below comes down to one thing: write it down as it happens. An expense logged on the way out of the restaurant takes ten seconds; reconstructing it in October from a bank statement takes an afternoon and ends in guesswork.

The method, in four rules

1. Every expense carries the name of whoever paid

The same person does not have to pay, and you do not have to take turns. All that matters is that the entry says what, how much and who. Usually whoever books something pays for it — the hotel, the car, the flights — and day-to-day things go on whichever card is closest to hand.

2. Each expense is split only between the people who used it

This is the rule that prevents 90 % of arguments. If three of the five go on the boat trip, that boat trip is divided by three. If one person does not drink, the two bottles of wine are not theirs. A common pot split equally sounds easier, and it is exactly what produces the line "well, I barely…".

3. Currencies, at that day’s rate

Log it in the currency it was paid in — 3,200 baht is 3,200 baht — and convert for the total. Converting by eye, or using last week’s rate, is the most common mistake on longer trips and the hardest to spot afterwards, because the numbers still look plausible.

4. Settle once, at the end

Do not pay each other during the trip. Every mid-trip transfer is one more thing somebody has to remember. When you get back, look at the list, work out the split, and make the two or three transfers it comes to.

The three kinds of split

Split	When to use it	Where it breaks
Equally	Accommodation, rental car, fuel, the supermarket shop	When somebody arrives a day late or leaves early
Only between those who used it	Day trips, tickets, dinners not everyone goes to	If it is not logged at the time, there is no way to reconstruct who went
By night or by leg	Trips where people join and leave on different dates	You need everyone’s dates clear from the start

The awkward cases, solved

Somebody arrives a day late. Divide accommodation by nights occupied, not by people. Five people and four nights is twenty person-nights; everyone pays for theirs.
Someone brings their own car. Agree a figure before you leave — fuel and tolls, plus something for wear if you like — and log it as an expense like any other. What does not work is leaving it at "we’ll sort it out": nobody asks, and the owner ends up paying for all of it.
The person who does not drink. Ask for drinks on a separate bill, or log the meal and the drinks as two entries. Two lines instead of one.
One person fronts far more than everyone else. Normal, when a single booking is €1,200. Do not fix it with mid-trip transfers: it comes out in the final split.
Tips and rounding. Let them go. If the gap is two euros, the time spent arguing is worth more than the two euros.

One thing worth discussing before you go: the spending level. Not the split — that is mechanical — but whether this is a hostels-and-markets trip or a hotels-and-restaurants one. It is the only genuinely awkward conversation, and it is far cheaper in March than at the destination.

How OhMyWay does it

Every expense is logged with who paid and in which currency, and converted at that day’s rate to give the real total for the trip. Expenses break down by category, with what each person has put in, and bookings that have a price count as an expense without being entered twice. Because the group shares the same trip, anyone can add theirs from their own phone, and it works offline: the expense is logged there and then even with no signal, and syncs when there is one.

If splitting costs is all you need, see how it compares with Splitwise. And if the trip is still being planned, start with how to plan a group trip.