Income-proportional expense split
Calculate each person's fair share of shared expenses based on their income — proportional, equal 50/50, or a hybrid of both.
Why split expenses proportionally?
When two people share a rent but earn very different incomes, a strict 50/50 split can feel unfair. A proportional split (or prorata) assigns each person a share that mirrors their ability to pay. For example, if Alex earns €3,000/month and Sam earns €1,500/month, a proportional split of a €1,200 rent gives Alex €800 and Sam €400 — exactly the same 66%/33% ratio as their incomes.
How the calculator works
Enter each person's monthly income (or any common income period) and the total shared amount. Choose a mode — proportional, equal, or hybrid — and the calculator shows the exact amount each person should contribute. The hybrid mode averages the proportional and equal shares, useful when you want to account for income differences without going fully proportional.
Worked example
Alex earns €3,000/month, Sam earns €1,500/month. They share a €1,200/month rent.
| Name | Monthly income (€) | Proportional (by income) | Equal (50/50) | Hybrid (average) |
|---|---|---|---|---|
| Alex | €3,000 | €800 (66.7%) | €600 (50%) | €700 (58.3%) |
| Sam | €1,500 | €400 (33.3%) | €600 (50%) | €500 (41.7%) |
Calculator
Save this split in Boney
Every expense is then shared by these shares, without redoing the calculation. Free for two, on iPhone and Android.
