When two people earn different amounts, "we split everything 50/50" quietly means the lower earner gives up a bigger slice of their life. The calculator above takes your two net incomes and your joint bills, and shows three defensible ways to divide them — not just the answer, but what each of you has left afterwards, which is the number the fairness argument is actually about.
How the calculator works
Enter what each of you actually receives per month — after tax, not the salary in the contract — and list the bills you genuinely share: rent, utilities, groceries, the streaming plan you both watch. The calculator then shows all three methods side by side. Tap one and every bill is divided by that rule, to the cent: each bill is rounded with the largest-remainder method, so the two shares always add up to the bill exactly instead of leaving a stray cent.
The three ways to split
50/50 — same amount each
Each partner pays half of every bill. It is the simplest rule, it needs no income disclosure, and while your incomes are close it is genuinely fine. The catch appears as the gap grows — the same euro amount is a different sacrifice for each of you, and the section below puts a number on that.
By income — same share of income
Each partner pays the share of the bills that matches their share of the combined income. If you bring in 58% of the money, you cover 58% of every bill. Both of you give up the same percentage of what you earn, rather than the same amount — which is what most people mean when they say a split "feels fair" despite unequal pay.
Equal leftover — same money left over
The third method asks a different question: what division leaves both of you with the same amount after the joint bills are paid? The higher earner's share works out to (bills + income gap) ÷ 2, capped between zero and the whole bill total. It is the most aggressively equalizing of the three — and it has an honest limit: when the income gap is bigger than the bills, even paying 100% of them leaves the higher earner ahead. The calculator says so out loud instead of pretending the numbers balanced; truly equal leftovers would need a transfer beyond the bills, which is a bigger conversation than a bill split.
A worked example
Alex takes home €2,800 a month and Sam €2,000, so Alex earns 58.3% of their combined €4,800. Their joint bills are €1,100 rent, €160 utilities and €240 groceries — €1,500 a month. The three methods give:
- 50/50: each pays €750. Alex keeps €2,050, Sam keeps €1,250.
- By income: Alex pays €875 (58.3%), Sam pays €625. Alex keeps €1,925, Sam keeps €1,375 — both gave up 31.25% of their income.
- Equal leftover: Alex pays (€1,500 + €800) ÷ 2 = €1,150, Sam pays €350. Both keep exactly €1,650.
None of these is "the correct" answer — they are three different definitions of fair, and the right one is whichever both of you can say yes to. The point of seeing them together is that the choice becomes explicit instead of defaulting to 50/50 because nobody did the arithmetic.
When 50/50 stops being fair
In the example above, the same €750 costs Sam 37.5% of their income but Alex only 26.8%. That gap is invisible in the bill amounts and very visible in day-to-day life: one partner is saving while the other counts days to payday. This is why financial planners commonly point couples with meaningfully different incomes towards splitting according to income and revisiting the ratio as incomes change (CNBC, 2023). If even a proportional split leaves one of you squeezed, that is what the equal-leftover column is for.
Keep the ratio going, not just the number
A calculator answers once; bills arrive monthly. Continue in Dolio turns what you typed into a shared group — each bill becomes an expense with your chosen split already attached, and nobody needs an account just to look at it. From then on, new expenses can carry the same ratio.
Weighted shares in Dolio
Frequently asked questions
Should we use gross or net income?
Net — what actually lands in your account after tax and deductions. Two identical gross salaries can net very differently across tax situations, and the bills get paid out of net money. If one of you has irregular income, use a conservative monthly average and revisit it.
What if one of us has no income right now?
A strict by-income split then charges the earning partner everything, and the calculator flags this rather than hiding it. For a planned gap — study, parental leave, a sabbatical with savings — many couples agree a fixed contribution from savings instead. The math can't decide that; it can only show you what each rule implies.
Do we need to recalculate when an income changes?
Yes — the ratio is only as current as the incomes behind it. A raise, a job change or dropped hours all shift it. Re-running the numbers takes under a minute; a common rhythm is once a year plus after any big change.
Which bills count as joint?
Only what you genuinely share: housing, utilities, shared groceries and subscriptions you both use. Personal spending — your own phone, hobbies, debt from before the relationship — stays out. The split only feels fair if both of you would recognize every line on the list.
Does this work for three or more people?
The calculator is built for two, because the equal-leftover method is a two-person equation. The proportional idea generalizes fine: in Dolio, weighted shares work for any group size — give each person a weight matching their income and every expense splits proportionally.