Household chore rotation calculator

A household chore rotation calculator turns a list of chores, an ordered roster of people, and a week index into a fair weekly assignment so dishes, trash, and vacuuming do not stick to the same person forever. You paste the duties and the names in rotation order, choose which week of the cycle you are planning, and the tool assigns every chore with modular arithmetic that slides the roster under the chore list. Over a full cycle equal to the roster size, each person does each chore exactly once, which is the fairness property families, housemates, and shared flats actually want.

How the rotation assigns every chore fairly

Household chores become unfair when the same roommate always does dishes and someone else always forgets the trash. A rotating assignment is a fixed pairing rule, not a negotiation: take the chore list in the order you wrote it, take the roster in the order you wrote it, and slide the roster under the chores by the week index. Week zero lines the first person under the first chore, the second under the second, and so on, wrapping when there are more chores than people.

Week one shifts everyone one slot, so the second person inherits last week's first chore, the third person inherits the second, and the first person picks up whatever fell off the end of the list. After a number of weeks equal to the roster size the slide has visited every alignment exactly once, which means each person has done each chore exactly once. That is the fairness guarantee: it does not depend on calendars, holidays, or who complained last Sunday.

If there are more people than chores, some names rest that week, and the rest slots themselves rotate so the same person is not forever off duty. If there are more chores than people, some names receive more than one chore that week, and those extras also rotate through the roster. The calculator never invents skip weeks, weights, or vacation calendars; if someone is away, remove them from the roster or advance the week index in your own layer.

Because the rule uses only integer remainder, two households that share the same lists and the same week counter will always agree on the same sheet, even if they print it in different kitchens.

Where a fair chore rotation helps

Shared flats post a weekly sheet so nobody can claim they did not know whose night it was to take out the bins. Families with teenagers rotate kitchen, laundry, and pet duties without rewriting a paper chart every Sunday. Landlords and property managers of student houses publish a deterministic rota that new tenants can recompute from the same lists and a week counter stored in the house chat.

Product teams that ship chore-chart apps need a tiny oracle that marks the same pairing for the same inputs instead of a spreadsheet that only one person updates. Prefer this capability when you already know the duties and the people and only need the fair pairing for a given week; it is not a calendar, not a reminder service, and not a points or allowance ledger.