One Splits, One Picks: A Two-Room Rent Split Test
For this made-up two-room example, an equal split makes both roommates prefer Room A. Setting Room A's rent at $1,300 and Room B's at $1,100 changes the model: one roommate prefers A by $100, while the other prefers B by $100. The two amounts still add to the entered $2,400. These are self-created inputs, not real renter data or an industry rule.
The test inputs
The model compares each person's entered dollar value for Room A with Room B, then subtracts the rent difference. It tests whether a proposed price difference matches the preferences entered for this example.
| Input | Roommate A | Roommate B |
|---|---|---|
| Entered value for Room A | $300 | $100 |
| Entered value for Room B | $0 | $0 |
Entered total rent: $2,400. Proposed Room A premium: $200. Both are hypothetical inputs created for this worked test.
Compare the two splits
| Scenario | Room A rent | Room B rent | A's Room A margin | B's Room A margin | Rent check |
|---|---|---|---|---|---|
| Equal split | $1,200 | $1,200 | +$300 | +$100 | $1,200 + $1,200 = $2,400 |
| Proposed difference | $1,300 | $1,100 | +$100 | −$100 | $1,300 + $1,100 = $2,400 |
The margin is calculated as: (entered value for Room A − entered value for Room B) − (Room A rent − Room B rent). A positive result means Room A wins under the inputs; a negative result means Room B wins. With equal rent, both entered values favor Room A. With a $200 rent difference, the modeled preference margins separate.
Try different inputs
Change the total, rent premium, or room-value differences. All fields are hypothetical; the page does not save your entries.
Equal split
Room A: $1,200.00 · Room B: $1,200.00 · A's margin: +$300.00 (Room A) · B's margin: +$100.00 (Room A) · Total: $2,400.00
Proposed split
Room A: $1,300.00 · Room B: $1,100.00 · A's margin: +$100.00 (Room A) · B's margin: −$100.00 (Room B) · Total: $2,400.00
If an equal split leaves one cent, Room B receives that remainder cent in this model. If rent plus the proposed premium cannot be split evenly to cents, the calculator reports an input error instead of silently changing the figures.
How to run a one-splits, one-picks conversation
One roommate proposes two room prices that add to the full rent. The other roommate chooses the room they prefer at those prices. The proposer takes the room left over. For this example, the proposed prices are $1,300 for A and $1,100 for B. With the entered values above, the chooser model favors B, leaving A for the proposer.
This page presents a self-built decision exercise, not a published standard or a guarantee that two people will agree. The entered values are subjective assumptions; they are not an appraisal of either room. If the residents use different priorities, change the input values and rerun the comparison instead of treating these amounts as a recommended rent schedule.
Reproduce the arithmetic
For each person, subtract Room B's entered value from Room A's entered value, then subtract the difference between the two room rents. The sign of the result shows that person's model preference. Both room prices must add to the entered total rent.
The tested JavaScript model is available at the model source. SHA-256: 417374ea0581a17f5f1ee11912b0b7f78b01ee18ce6cf0ba83439aaa3051799d. The complete input and output record is available as JSON.
For a calculator that compares room, area, and income allocation across several participants, use the rent split calculator. This page answers a narrower question: whether two people rank two rooms differently after a proposed rent difference.
Four preference patterns at fixed rents
Keep Room A at $1,300 and Room B at $1,100 in every row; total rent remains $2,400. The room-only preference differences use the existing hypothetical values: Roommate A is +$300 for A or −$300 for B, and Roommate B is +$100 for A or −$100 for B. After rent, calculate each margin as room-only difference minus $200. A positive margin means Room A; a negative margin means Room B. These are model margins, not cash losses or observed renter data.
| Room-only preference (A / B) | Same room-only preference? | After-rent margin (A / B) | Final preference (A / B) | Chooser B picks | Proposer A gets | Outcome |
|---|---|---|---|---|---|---|
| Room A / Room A | Yes | +$100 / −$100 | Room A / Room B | Room B | Room A | Split: they choose different rooms after rent. |
| Room A / Room B | No | +$100 / −$300 | Room A / Room B | Room B | Room A | Split: they choose different rooms after rent. |
| Room B / Room A | No | −$500 / −$100 | Room B / Room B | Room B | Room A | Collision: A is left with Room A despite a negative margin. |
| Room B / Room B | Yes | −$500 / −$300 | Room B / Room B | Room B | Room A | Collision: A is left with Room A despite a negative margin. |
With these fixed prices and inputs, the first two combinations separate after rent; the last two collide on Room B. In either collision, B chooses B and A receives A, with A's modeled margin at −$500. The mechanism cannot make both preferences fit one room allocation when both people still favor the same room after rent; this calculation also cannot predict how real roommates will value a room.
Limits to keep in view
The model does not determine a legal rent obligation, amend a lease, establish a room's market value, or predict a household's decision. It handles two rooms and two people only. It does not include shared rooms, utilities, deposits, or extra fees. Use the result as a discussion worksheet and check any written rental agreement separately.
What this run establishes
- Under the recorded equal-rent inputs, both modeled margins favor Room A: +$300 and +$100.
- Under the recorded $200 Room A premium, the margins are +$100 and −$100.
- The proposed room prices reconcile exactly: $1,300 + $1,100 = $2,400.
Each point is specific to the saved input set and linked model code. No claim is made that similar calculations or methods are absent from the wider web.