On a trip, in a shared house or as a couple, each person pays for different things. There are two common ways to split costs and a simple method to settle up.
Equally
Each person’s share is total ÷ number of people. If Ana paid 120, Luis 45 and Marta nothing, the total is 165 and each share is 55.
Proportional to income (or another criterion)
Each person takes a share proportional to a “weight”: salary, days stayed or an agreed percentage.
With salaries of 1,800, 1,200 and 1,500 (sum 4,500), Ana pays 165 × 1,800 ÷ 4,500 = 66, Luis 44 and Marta 55.
Balances and transfers
Each person’s balance is what they paid minus their share. With an equal split: Ana +65, Luis −10, Marta −55. People with a negative balance pay those with a positive one, largest first: Marta pays Ana 55 and Luis pays Ana 10. Two transfers and everyone is square.
Avoiding arguments
- Agree on the method before you start spending.
- Log every expense the same day.
- Round to cents at the end, not at every step.
The shared expenses splitter does all of this and gives you the list of transfers.