Rent split calculator
Splitting rent evenly only works when the bedrooms are equal, and they almost never are. Enter the rent and what each room actually is: how big, whether it has its own bathroom, whether someone's sharing it. It works out a monthly figure per person. Then it gives you a message to send the group chat before anyone signs.
How the split works
Part of the rent isn't for any bedroom. The kitchen, the living room, the hallway. Everyone uses those the same amount, so that slice comes off the top and is split evenly by headcount. You pick how much of the place that is, from Tiny at 25% to Huge at 65%, with Average at 45%, which is roughly what the shared rooms come to by floor area in a typical apartment, once you count the hallways and the bathrooms.
The rest is divided between the bedrooms by weight. Bedroom size sets the base, and the things that make a bedroom better or worse multiply it: a private bathroom adds 25%, a private half bath 10%, a missing window takes 12% off. If two people share a bedroom, they split that bedroom's figure between them, but each still pays a full share of the common space and the utilities, because they each use those.
The weights, in full
These are the actual numbers the calculator uses. The size weights are square feet, so the labels mean something you could go and measure. And if you already know a bedroom's footage, switch the calculator to Sq ft and type it instead.
| Room size | Weight |
|---|---|
| Tiny | 60 |
| Small | 85 |
| Smallish | 100 |
| Normal | 120 |
| Generous | 145 |
| Large | 180 |
| Huge | 230 |
| Then multiplied by | |
|---|---|
| Private bathroom | ×1.25 |
| Private half bath | ×1.10 |
| Shared bathroom | ×1.00 |
| No window | ×0.88 |
| Great light | ×1.06 |
| No closet | ×0.94 |
| Large closet | ×1.06 |
So a Normal bedroom with a private bathroom comes to 150; a Small one sharing a bathroom, with no window, comes to 75. Windows and closets sit behind the bedroom number in the table. Tap it to open them. Utilities, if you enter them, are split evenly on top: weighting a power bill by closet space would be indefensible.
We publish these because a number you're going to divide real money with should be arguable. If the group thinks a private bathroom is worth more than 25% where you live, that's a reasonable thing to say out loud, and easier to say when you can see the figure rather than guess at it.
How the number is worked out
Six steps, in order. Nothing else is applied, and the figures below are the ones the calculator above actually uses.
- Set the shared space aside. Decide how much of the place is kitchen, living room, hallways and shared bathrooms. Average is 45%, so on $3,000 of rent that's $1,350.
Shared space Of the rent Roughly Tiny 25% A galley kitchen and not much else Small 35% A small living area, one bathroom Average 45% A normal living room, kitchen and bathroom Large 55% A big living space, or a second bathroom Huge 65% A great room, a den, more than one bathroom - Split the shared space and utilities evenly, by person. Not by bedroom. Two people sharing one each use the kitchen, and each run the hot water. Three people on $3,000 of rent and $300 of utilities: $450 and $100 each.
- What's left belongs to the bedrooms. $3,000 less the $1,350 leaves $1,650 to divide between the bedrooms.
- Give each bedroom a score. Start with its size in square feet, then multiply for what it has: a private bathroom ×1.25, a private half bath ×1.10, no window ×0.88, great light ×1.06, no closet ×0.94, a large closet ×1.06. See the full list of weights above.
- Share out the bedroom money by score. A bedroom gets $1,650 multiplied by its own score divided by all the scores added together.
- Take the bedroom cost, and divide by the number of people sharing it. Then add that person's share of the shared space and their cut of the utilities. That's what they pay.
The same thing with real numbers
$3,000 rent, $300 utilities, three bedrooms with one person each, all the same size and sharing a bathroom, shared space on Average:
| Shared space, 45% of $3,000 | $1,350, so $450 each |
| Left for the bedrooms | $1,650 |
| Each bedroom scores 120, and there are three | $1,650 ÷ 3 = $550 a bedroom |
| Utilities, split evenly | $100 each |
| Each person pays | $1,100 |
Now take the window out of bedroom 3. Its score drops from 120 to 105.6, the three scores total 345.6 instead of 360, and the bedroom money shares out differently: bedrooms 1 and 2 get $573 each and bedroom 3 gets $504. Add everyone's $450 of shared space and $100 of utilities and it comes to $1,123, $1,123 and $1,054, still $3,300 between them.
One bedroom losing a window moves it $46 and costs the other two $23 each. That's the whole thing. No hidden terms, no fudge factor.
When you don't need this
If the bedrooms are genuinely comparable, split it evenly and skip the conversation. The arithmetic is worth doing when one bedroom is meaningfully better, an ensuite or double the floor space, or when someone's taking the smallest bedroom to keep the rent down, or when the gap would move anyone by more than about ten percent of their share.
Agree it before you sign, not after. Once the lease is signed it's hard to change things around; beforehand it's just logistics, and the person taking the small bedroom gets to choose it knowingly.
Then there's everything else
Rent is one number, agreed once a year. The bulk of the splitting is everything after it: groceries, the wifi bill, the person who always buys the paper towels. Tabster keeps a running tab between roommates: add costs as they happen, claim what's yours, and settle up whenever without anyone keeping a spreadsheet.
Wondering what the number normally comes out to? How much less you should pay for the smaller bedroom works it through. Or see how shared costs land on one balance, or the other calculators.
