Split expenses by income
Divide any shared cost in proportion to what each person earns.
Income
Enter the amount to split to see the split.
Proportional splitting divides a cost by what each person earns rather than by headcount. Enter the total and each person's income, and the calculator shows both the percentage and the amount.
The argument for it is that an even split of a $2,000 rent is a very different burden on $40,000 than on $120,000. The argument against it is that it makes every shared cost depend on a number people find private. Households land in both places, and both are reasonable.
How the percentage is worked out
Each person's share is their income divided by the household's combined income. Two people earning $75,000 and $45,000 have a combined $120,000, so they pay 62.5% and 37.5%. On a $2,000 rent that is $1,250 and $750.
The percentages are calculated from the amounts rather than the other way round, so the shares add up to the total exactly even when the ratio produces awkward decimals.
Gross, net, or something else
Gross pay is simpler to state and easier to verify. Net pay reflects what people can actually spend, which is the point of splitting proportionally in the first place, and it accounts for very different tax situations or a large student-loan deduction.
Net is the more defensible choice for most households. Whichever you pick, use the same basis for everyone and revisit it when someone's situation changes rather than renegotiating in the middle of an argument about a specific bill.
Variable and irregular income
Freelance and commission income makes a month-by-month proportional split volatile. A trailing twelve-month average is the usual fix: it smooths out good and bad months and only needs recalculating a few times a year.
Some households instead agree on a fixed percentage for a year at a time, recalculated each January. That trades a little accuracy for the ability to plan, which is usually the better deal.
Questions
- How do you split bills based on income?
- Add both incomes together, divide each person's income by that combined figure, and apply the resulting percentage to the bill. Someone earning twice as much pays twice as much.
- Should we use gross or net income?
- Net is usually the more defensible basis, because it reflects money actually available to spend and accounts for different tax and deduction situations. Gross is simpler. Use the same basis for everyone.
- Is proportional splitting fairer than splitting evenly?
- It equalises the burden rather than the amount. Whether that is fairer depends on what the household is trying to equalise, and it is worth agreeing on explicitly rather than assuming.
- What if one person's income changes a lot month to month?
- Use a trailing twelve-month average, or fix the percentages for a year and recalculate on a set date. Recalculating every month makes budgeting difficult for both people.
- Do we have to split everything proportionally?
- No. Many households split fixed costs like rent proportionally and keep variable ones like groceries even, which avoids attaching an income calculation to every trip to the shop.
When one calculation isn’t enough
A calculator answers a single question. Make It Even keeps the answer current: add expenses as they happen, split each one however it needs to be split, and everyone sees the running balance. It handles multiple currencies using the exchange rate from each expense’s own date, so old totals never drift.
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