Split the rent fairly, by room size or by income
Enter the rent and who lives there. See what each person pays under four common methods — and watch the shares add up to the total, exactly.
Free · No signup · Runs entirely in your browser
How this differs from an even split. Each row shows what that person pays versus an even split — switch between the four buttons above and watch the numbers move. Bigger private rooms cost more, and shared space costs everyone the same; that is the whole principle behind the by-room method. The shares always add up to the total rent exactly; if they ever don't, the tool says so. This calculator divides rent between the people you list — it is not legal or tenancy advice, and a rent split is whatever the people signing the lease agree to.
How rent splitting actually works
A rent splitter answers one question the moment three people are standing in a flat deciding whether to take it: what does each of us actually pay? Most groups default to splitting evenly because it is the only method anyone can do in their head, but even split is rarely the fairest answer. If the rooms differ in size or the incomes differ a lot, an even split quietly overcharges someone every single month, and that is exactly the kind of thing that sours a house share six months in.
The arithmetic behind each method is short enough to check by hand. Splitting evenly is the total rent divided by the number of people. Splitting by room size adds an equal share of the common area to each private room, then divides rent by each person's effective area — with three rooms of 180, 150 and 120 square feet and 300 square feet of shared space, the shared space becomes 100 square feet per person, so effective areas are 280, 250 and 220 out of 750, giving $1,120, $1,000 and $880 on a $3,000 flat.
Splitting by income divides rent by each person's share of the household income — with incomes of $80,000, $60,000 and $40,000 out of $180,000, a $3,000 rent becomes $1,333.33, $1,000.00 and $666.66. The weighted method takes half of each: the room-size share and the income share are averaged, which lands the same three people at $1,226.66, $1,000.00 and $773.33. Notice that the middle roommate pays exactly $1,000.00 under three of the four methods, which is a useful sanity check when you are testing a split.
The four methods, and when each one is right
There is no single correct answer here, and the calculator will not pretend otherwise. The even split is the right choice when the rooms are genuinely comparable and everyone earns roughly the same — it takes ten seconds to explain and nobody has to think about it again for a year. The room-size split is the right choice when rooms differ, which is almost always the real disagreement in a shared flat. The income split is the right choice when people earn very different amounts and the group cares about equal burden rather than equal dollars.
The weighted method exists because many groups cannot agree between the last two, and averaging them is a defensible way to stop the argument. Try all four on your own numbers above — they take seconds — and notice which ones put someone in an uncomfortable position. That discomfort is usually the actual conversation you need to have, and having the number on screen makes it far easier to have it before the lease is signed rather than after.
| Method | Charges more for | Works best when |
|---|---|---|
| Split evenly | Nothing — equal shares | Rooms are comparable and incomes are similar |
| By room size | A bigger private room | Rooms differ in size — the most common real disagreement |
| By income | Higher earnings | Incomes differ a lot and the group wants equal burden |
| Room size + income | Both, half each | The group cannot agree between the two above |
Do not forget the shared space
Common areas are the part people forget. The kitchen, living room and bathroom are used by everyone equally, so charging purely by private room size would mean the smallest room pays the least for the space everyone shares. Adding an equal slice of the common area to each person's private area corrects this, and it is why the by-room method on this page asks for the shared square footage separately.
If you do not know your exact areas, measure or estimate — the split is not sensitive to small errors. A rough measurement of the private rooms and a rough guess at the shared space will land within a few dollars of the exact answer, and the principle, that bigger private space costs more while shared space costs everyone the same, is what actually matters.
Rent splitting questions, answered
How do you split rent between roommates?
The fairest split depends on what you and your roommates consider the difference between rooms. Three methods cover most shared flats. Splitting evenly is simplest and works when rooms are similar and incomes are comparable. Splitting by room size charges more for the bigger room, counting the square footage of each private room plus an equal share of the common areas. Splitting by income charges each person in proportion to what they earn, which keeps the housing burden roughly equal as a share of pay. A fourth option, weighting both room size and income equally, is a compromise many house shares settle on. Whatever you choose, the shares must add up to the total rent exactly — this calculator checks that sum for you.
Is it fair to split rent by income?
It is fair if the people involved agree to it, and it has one clear virtue: it equalises the burden rather than the dollars. If rent is $3,000 and two roommates earn $80,000 and $40,000, splitting evenly costs the lower earner 18% of their income while the higher earner pays only 9%. Splitting proportionally charges $2,000 and $1,000 — the same 25% of each person's pay, which is why it feels fair to many houses. The trade-off is that a proportional split rewards higher pay with higher rent, which some people dislike on principle, and it has to be revisited every time someone's income changes. It also works poorly if one person's income is irregular or if someone is between jobs.
Should the biggest room pay more rent?
Yes — this is the most widely accepted principle in shared housing, and it is the basis of the room-size method. The standard way to price it is not to charge purely for the private room, because everyone uses the kitchen, bathroom and living space equally. The usual approach is to add an equal share of the common area to every person's private room size, then divide the rent by that total. Suppose three people have rooms of 180, 150 and 120 square feet and the shared space is 300 square feet. The shared space splits to 100 square feet each, so the effective areas become 280, 250 and 220 out of 750 — rents of $1,120, $1,000 and $880 on a $3,000 flat. The person with the largest room pays $240 more than the smallest, which most house shares consider reasonable.
How do you handle a couple sharing one room?
The common approach is to treat the couple as roughly one and a half tenants rather than one or two. They occupy one private bedroom but two people use the kitchen, the bathroom and the living room, so charging them a single share undercharges the common areas while charging them two full shares overcharges the bedroom. A practical compromise is to give the couple a single room-size share plus one extra half-share of the common area for the second person. Whatever formula you land on, write it down before anyone signs the lease — the number matters far less than everyone having agreed to the same rule in advance.
What if one roommate moves out mid-lease?
The lease usually binds everyone who signed it, so a departing roommate is still liable unless the landlord agrees to release them — check the lease before assuming a replacement solves it. In practice, most shares do three things: find a replacement tenant, agree with the landlord in writing on the swap, and re-run the split so the remaining people know exactly what they now owe. The remaining tenants absorb the departed share in the meantime, so it is worth agreeing up front how a vacancy gets covered and how long that arrangement lasts before someone is expected to move out or the group re-lets the room.
How do you split utilities and shared costs?
Utilities split most naturally by the same method you use for rent, because the argument for each is the same: electricity and water are consumed by people, so a proportional or even split fits, while a room-size split makes less sense for a bill that does not scale with square footage. Many shares use a hybrid — rent by room size, utilities evenly — which is simple to explain and to check. However you divide them, keep fixed subscriptions (internet, streaming, cleaning) separate from usage-based bills, since the first is trivially even and the second is not. Include the total cost of utilities when you agree the split, not after the first bill arrives.
