Couple expense split calculator

How the math works (you can do it on paper)

Fifty-fifty split: each person takes half of the shared expenses. Simple and direct — usually perceived as fair when incomes are similar.

Income-proportional split: add both incomes; divide each income by that total to find their percentage; multiply the percentage by the expense total. Example: incomes of 6,300 and 2,700 add up to 9,000 — so 70% and 30%. Over 4,500 of expenses, the shares are 3,150 and 1,350.

Month-end settlement: compare what each person PAID with their share. Whoever paid less than they owed transfers the difference to the other. In the example above, if the first person paid 2,400 (share of 3,150), they transfer 750 — and the month balances.

Which model to choose

The calculator does not decide for you, and no model is universally fairer. Fifty-fifty is simpler to maintain; the proportional one preserves the same relative breathing room when incomes differ — in the simulation above, fifty-fifty would consume 83% of the income of whoever earns 2,700, while the proportional model leaves both committing 50% of their own income.

The guide on how to split couple expenses (in the content hub) compares the models in more depth, adds splitting by category and covers the most common mistakes.

What counts as a shared expense

Before calculating, agree on which costs belong to life together. Housing, household bills, groceries, family transportation, children, pets and services used by both often count. Personal purchases, debts from before the relationship and expenses in which the other person did not take part do not have to be split automatically.

The agreement can vary by category: rent proportional to income, groceries fifty-fifty and a personal expense outside the split, for example. What matters is using the same rule when entering the total and recording how much each person paid, so the math is not correct over a base the couple does not recognize.

• First list only the expenses both people consider shared.
• Define personal exceptions before adding up the monthly total.
• Review the agreement when income, housing or responsibilities change.

Privacy: the numbers do not leave this page

The whole calculation runs in your browser. Incomes, expenses and payments are not sent to any server, are not saved and do not enter any metric — the only thing recorded is that the tool was used, with no values attached.

The summary the button copies goes to your clipboard: you choose whether and with whom to share it. And the obvious: the result is a simulation with the values you typed, not personalized financial advice.

After the math comes the routine

A calculator solves the month; the challenge is keeping the agreement alive through the year — recording who paid what, handling installments that cross months and reaching the close without rebuilding everything from memory.

That is where ClariFin comes in: the agreed percentage is saved on the family, every entry keeps who paid and who took part, and the month’s settlement shows up calculated. The product is free and you can create your account now.