How to split group bills: the method, and a free app with no sign-up

When you split group bills one at a time, a single weekend turns into a pile of small debts running in every direction. The way out is to stop paying back bills and start paying off balances. Everyone logs what they paid, the sums are done once, and the group settles with a handful of payments.

How to split group bills in four steps

1. Log every bill with who paid and who it was for. Those are the two facts people forget first, so write them down the same day.
2. Divide each bill between only the people it was for. Someone who skipped the boat trip pays nothing for it. Work in cents, so the parts add back to the exact total.
3. Work out each person’s balance. Add up what they paid, and subtract the sum of their shares. A positive balance means the group owes them. A negative one means they owe the group.
4. Settle the balances, not the bills. The person who owes the most pays the person owed the most, as much as one of them can clear. Repeat until every balance is zero.

Step four is where the saving is. The order of the bills no longer matters, and neither does who paid for which dinner.

A worked example: five friends, five bills

Ana, Ben, Carla, Dev and Eli spend a weekend away. Different people pay for different things, and three of them go on a boat trip.

The four shared bills come to €170.00 a person, and the boat trip adds €30.00 for the three who went. Paid minus share gives each balance:

Two checks: the shares add up to €940.00, the total spent, and the balances add up to zero. If either fails, a bill was entered wrongly.

Paying back each bill separately would take 18 payments. Settling the balances takes three:

Ben never pays Dev for the boat, and Ana never pays Eli for dinner. Those debts cancel out inside the balances. The method is explained further in settling up with the fewest transfers.

When different groups need different splits

An equal split is a good default, but it is not always the fair one.

• Friends on a trip: split equally, but only between the people who were there. Personal extras stay out of the list. There is more in splitting costs on a group trip.
• Families and couples in a bigger group: use shares. A couple counts as 2 and a single friend as 1, or a family of four as 4, so nobody has to invent a fair percentage.
• Roommates: split utilities equally, and split rent by shares or exact amounts when the rooms differ. See splitting rent by room size.
• A dinner where orders were very different: use exact amounts per person. The usual cause is drinks, as splitting a restaurant bill shows.
• A party or a gift: the guest of honor is simply left out of the split, so the others cover their part.
• Bills in different currencies: agree one group currency and convert each bill at the rate actually paid, as in splitting expenses in several currencies.

Whatever you choose, agree it before the bill arrives. The split itself rarely causes the argument. Finding out about it afterwards does.

A free app to split group bills, or a spreadsheet?

For a short list of bills, a spreadsheet or the bill split calculator is enough. A shared app helps when there are several payers and more than a day or two of spending, because nobody has to be the one who keeps the list up to date.

kisir is built for this. It is free with no ads, and there is no sign-up: people pick a name and join by link, QR code or six-character code. Each bill can be split equally, by shares or by exact amounts, in any currency, and bills added offline sync later. The app shows the fewest payments that settle the group, in 20 languages. Download it for iPhone or Android.