Guides to settling up after a trip

The calculators do the arithmetic. These guides are about the decisions around it, the ones a group usually argues about after the money is spent: which exchange rate is fair, who carries a share that was not for everyone, what an empty room costs. Each guide works through one question with real numbers, and ends with how the calculator handles it. The exact rules are on the methodology page.

Start with your situation

• You are back from a trip abroad and the receipts are in three currencies. Read Which exchange rate to use first, then use the trip settle-up.
• The trip ended months ago and nobody has settled yet. Read What settling up late costs first, then use the trip settle-up.
• Someone covered a friend's ticket or lent cash during the trip. Read When one friend pays for another first, then use the trip settle-up.
• The trip has not happened yet and you want to avoid an argument later. Read What to agree before a group trip first, then use the exchange-rate guide.
• The group is treating someone: a birthday, a bachelorette, a farewell. Read Splitting a trip when the group treats someone first, then use the guest of honor calculator.
• A roommate is moving out and the last rent, bills and deposit are open. Read Prorated rent when a roommate moves out first, then use the move-out calculator.
• One dinner or a night across several bars, and someone ordered much more than the rest. Read Split evenly or by what each ordered first, then use the restaurant bill splitter.
• A road trip in one car, with a driver who wants a break on the fuel or a friend who joined for one leg. Read Should the driver pay less for gas first, then use the road trip gas calculator.
• The result says three transfers and someone asks why not two. Read What "fewer transfers" does first, then use the transfer rule.

Money in other currencies

Most trip arguments that look like arithmetic are really about which rate was used. These two guides measure it.

• Which exchange rate to use when you settle a trip
  Answers: Should a receipt be converted at the rate of the day it was paid, the day you settle, or the day the card statement shows it?
  The day it was paid, the day you settle, or the day the card statement shows it. Why the three give different answers, and which one to pick.
• What settling up late costs: two years of exchange rates, measured
  Answers: How much does waiting a week, a month or three months change what each person sends?
  Two years of daily reference rates, measured: how much a receipt changes in value if the group settles a week, a month or three months later.

Who pays for whom

The receipts are rarely the hard part. The hard part is the payments that were not for everyone.

• When one friend pays for another on a trip
  Answers: Is a ticket bought for a friend a shared cost or a loan, and how do you avoid someone paying twice?
  A card that will not work, a ticket bought for two, cash lent at the market. Two ways to handle these small loans, and the mistake that makes someone pay twice.
• Should the driver pay less for gas? A fair way to split fuel on a road trip
  Answers: Should the driver pay less for fuel, does the car owner get anything for wear, and what does a friend who rode one leg owe?
  The same 500 km trip split evenly, with the driver paying half a share, and with the driver paying nothing toward fuel, plus what a friend who joined for the last 100 km owes. When each is fair, with both sides.
• How to split a birthday or bachelorette trip when the group treats someone
  Answers: When the group treats someone, who carries their share of an activity not everyone joined?
  A birthday weekend, a bachelor or bachelorette trip, a farewell. What groups usually agree, who pays the guest of honor's share of an activity not everyone joined, and a full weekend worked through to the last transfer.
• What to agree before a group trip, so settling up stays friendly
  Answers: Which rules are worth saying out loud before anyone books, and how do you put them in one message?
  Drinks, rooms, people who join late, card fees, exchange rates. Where the arguments start, and a message you can paste into the group chat before the trip.

Beyond the trip

The same rules apply to other costs a group shares once and then has to settle.

• Split the bill evenly or by what each person ordered? A fair way to settle a group dinner
  Answers: Should a group dinner be split evenly or by what each person ordered, and is the tip shared in proportion or per head?
  The same $144.00 dinner split evenly, by what each person ordered, and by order with a per-head tip, side by side. When each way is fair, and the arguments that come up at the table.
• How to calculate prorated rent and split the bills when a roommate moves out
  Answers: Who carries the rent for a room that stands empty, and is prorated rent counted on 30 days or the real days in the month?
  The daily-rate formula, real days or a 30-day month and who each suits, the case for and against the leaver paying for an empty room, the deposit when the lease goes on, and a full October move-out worked through to three transfers.

How the result is built

For the person who wants to check the list of transfers before sending money.

• What 'fewer transfers' settling does
  Answers: Why does nobody's total change when the debts are reduced to a few payments, and when does the simple method use one transfer too many?
  How a group's debts shrink to a few payments, why everyone's total stays the same, and the case where the simple method takes one transfer more than it needs.

Each guide shows the day it was published. A guide that turns out to be wrong is corrected, and the fix is listed on the corrections page.