How to use the trip cost splitter
- List each traveler and the total they paid toward shared costs such as lodging, rental cars and groceries.
- Leave each share at 1 for an equal split. Use another number to give someone a different part, for example 0.5 for a child who pays half.
- Read the fair share and the balance for each person, where a positive balance is money owed to them and a negative one is money they owe.
- Follow the settle up list of payments to bring every balance to zero.
Formula
Total = sum of what everyone paid
Fair share = total x traveler share / sum of shares (in whole cents)
Balance = paid - fair share
Shares are worked in whole cents. When the division leaves a remainder, the extra cents go to the travelers with the largest fractional remainders, earlier names first, so the shares add up to the total exactly.
Four travelers and $1,200 of costs
Alex paid $700, Sam paid $300, Jordan paid $200 and Casey paid nothing, so the total is $1,200.00. With equal shares each person owes $300.00. Balances are +$400.00 for Alex, $0.00 for Sam, minus $100.00 for Jordan and minus $300.00 for Casey.
Settling up takes two payments: Casey pays Alex $300.00 and Jordan pays Alex $100.00. For a total of $100.01 across three equal shares, the cents are shared as $33.34, $33.34 and $33.33.
Why the cents come out exactly
Dividing an amount by three leaves a fraction of a cent, which cannot be paid. A simple calculator rounds each share and the total can end up a cent too high or too low. This tool allocates whole cents by the largest remainder method, so the shares always add up to exactly what was spent. The extra cent goes to the earlier names when the remainders tie.
Unequal shares work the same way. A share of 0.5 means half a full share, so with shares of 1, 1 and 0.5, a $1,000 cost splits as $400.00, $400.00 and $200.00.
Settling up in fewer payments
The settle up list pairs the largest debts with the largest credits. It is a valid way to get everyone even, though not the only one, and it keeps the number of payments low. Payments happen outside this page, and the tool does not track who has paid whom.
It also does not convert currencies or itemize costs. For splitting one bill, see the tip calculator, and for sharing rent by room size, the rent split calculator. To plan the whole budget before the trip, use the trip budget planner.
Assumptions and limits
- Each amount entered is the total that traveler paid toward costs everyone shares.
- Costs are divided by share, with equal shares unless you change them.
- Amounts have at most two decimal places and shares at most two.
- Currency conversion and itemized costs are not handled.
Frequently asked questions
How do we split trip costs fairly?
Add up everything each person paid, divide the total among the travelers by their shares, and compare each fair share with what the person paid. The difference is what they owe or are owed.
What if someone should pay less, like a child?
Set their share to a smaller number, such as 0.5. Their fair share is then proportional to that number compared with everyone else's.
Why do the shares sometimes differ by a cent?
A total that does not divide evenly cannot be split into equal whole cents. The leftover cents go to some travelers so the shares add up to the exact total.
Does this tell me who should pay whom?
Yes, the settle up table lists one set of payments that brings every balance to zero. Other sets of payments could also work.