Family Expense Fairness Calculator

How the split is calculated

Three methods, and each one is a single share per person applied to every expense. Equal gives everybody one over the head count. Income-based gives each person their net monthly income over the household's total income, so somebody earning 3,500 alongside somebody earning 2,500 carries 58.3 per cent of every bill rather than half of it. Custom takes the percentages you type and uses them as given — the tool does not force them to add up to a hundred, so if they do not, the shares will not cover the bills. Your monthly figure is the total of all expenses multiplied by your share, and the annual figure is that times twelve. Between two and six people can be entered, and each expense is split by the same shares; there is no way to mark one bill as belonging to a subset.

The fairness check underneath is the point of the income method and it is worth reading before the split itself. It shows what each person has left after their share — income minus their part of the bills — because that is the number an income-proportional split is trying to equalise, and a fifty-fifty split on unequal incomes usually does not. It only appears on the income method, because the other two have no income to subtract from.

Nothing here is a benchmark and no figure is borrowed from anywhere. The default incomes and the starting expense amounts are placeholders to make the page usable on arrival, and the only numbers that mean anything are the ones you replace them with. The arithmetic also has nothing to say about unpaid work: if one person does most of the cooking, cleaning and childcare, that is a real contribution the income column cannot see, and the split it produces should be read with that in mind.

Every figure above was read out of the code that runs on this page. Where a number is our own judgement rather than a published one, the note says so and cites nothing. Method last checked 21 August 2026.