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Rent Split Calculator

Splits a total rent between housemates equally, in proportion to each person's room area (optionally dividing the common-area share equally) or in proportion to incomes, and returns per-person shares rounded to cents that add up exactly to the total.

Total rentTotal rent per period, in your currency. Method (optional)How to divide the rent. Number of people (optional)Number of tenants for the equal method (otherwise taken from the length of room_areas or incomes). Room areas (optional)Private room area per person in any one unit (m² or ft²), in tenant order; required for by_room_area. Incomes (optional)Income per person (same period and currency for everyone), in tenant order; required for by_income. Common area (optional)Shared space (kitchen, living room, bathrooms) in the same unit as room_areas; used by by_room_area. Split common-area rent equally (optional)true: the rent attributable to common_area is divided equally and only the private-room rent follows room size; false: the whole rent follows private room size.

When to use

Several people share a flat or house and need a defensible split of the rent by room size or income instead of a plain equal split.

Do not use when: You are splitting a one-off bill with a tip (use bill-split) or need utilities split by metered usage; this tool does not track deposits or running shared expenses.

Formula

equal: share_i = total_rent / n; by_income: share_i = total_rent × income_i / Σ incomes; by_room_area: common_rent = total_rent × common_area / (Σ areas + common_area) when common_area_share_equal else 0, share_i = common_rent / n + (total_rent − common_rent) × area_i / Σ areas; shares are rounded to cents with the largest-remainder method so that Σ share_i = total_rent

Proportional splits assume the rent scales with the chosen weight; the mixed rule (common-area rent shared equally, private rent by area) is the usual compromise for flats with unequal rooms. Percentages are shares of the total; fairness schemes based on bids (rental harmony) are not implemented.

Inputs

Parameter	Type	Required	Description
`total_rent`	number	yes	Total rent per period, in your currency. Range: ≥ 0, ≤ 100000000
`method`	enum: equal \| by_room_area \| by_income	default equal	How to divide the rent.
`people`	integer	no	Number of tenants for the equal method (otherwise taken from the length of room_areas or incomes). Range: ≥ 1, ≤ 100
`room_areas`	number_list	no	Private room area per person in any one unit (m² or ft²), in tenant order; required for by_room_area.
`incomes`	number_list	no	Income per person (same period and currency for everyone), in tenant order; required for by_income.
`common_area`	number	default 0	Shared space (kitchen, living room, bathrooms) in the same unit as room_areas; used by by_room_area. Range: ≥ 0, ≤ 1000000
`common_area_share_equal`	boolean	default true	true: the rent attributable to common_area is divided equally and only the private-room rent follows room size; false: the whole rent follows private room size.

Outputs

Output	Type	Description
`shares`	number_list	Rent per person in list order, rounded to cents so that they sum to total_rent.
`shares_table`	list	Per person: person, share, percent of the total and the weight used (1, room area or income).
`per_person_average`	number	total_rent / number of people.
`people_count`	integer	Number of shares.
`largest_share`	number	Highest individual share.
`smallest_share`	number	Lowest individual share.
`method_used`	string	Description of the split that was applied.

Example

3000 by room area 12 / 15 / 18: {"total_rent":3000,"method":"by_room_area","room_areas":[12,15,18]} → {"shares":[800,1000,1200],"per_person_average":1000,"people_count":3,"largest_share":1200,"smallest_share":800}

3000 by income 40,000 / 60,000: {"total_rent":3000,"method":"by_income","incomes":[40000,60000]} → {"shares":[1200,1800],"per_person_average":1500,"people_count":2}

GET https://tttkmbb.com/api/v1/calculate/rent-split?total_rent=3000&method=by_room_area&room_areas=12%2C15%2C18

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/rent-split (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/rent-split · Markdown: https://tttkmbb.com/everyday/rent-split.md · JSON definition: https://tttkmbb.com/everyday/rent-split.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="rent-split"
OpenAPI operationId: split_rent
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

FAQ

How is the common area handled?

With common_area_share_equal (default) the fraction of rent that corresponds to the shared space is split equally, and only the remainder follows room size: 3000 with rooms 12/15/18 m² and 30 m² of common space gives 880 / 1000 / 1120.

Why do the shares not equal total / people exactly?

Shares are rounded to whole cents; the largest-remainder method assigns the leftover cents to the people with the largest fractional parts so the shares still add up to the total.

Related calculators

Bill Split Calculator — Equal split of a bill with an optional tip.
Unit Price Comparison Calculator — Compare cost per square metre between flats.