Rent Split Calculator

How a rent split works

Rent is the biggest line in a shared household, and how four people divide it decides whether the year feels fair. A rent split is three decisions stacked on top of each other: which costs are shared, how much a bedroom is worth, and who absorbs the space everyone uses. The HUD rental help pages are a useful check on what a lease in your area normally covers.

Almost every lease lands on one of three methods.

• Even per person. Rent divided by the number of people. The person in the small room pays the same as the person in the big one, which is easy to explain and easy to resent by February.
• Even per room. Rent divided by the number of bedrooms. Each room's occupants then split their own room's share, so a couple pays the same for a room as a single person does.
• By square footage. Rent follows the size of each bedroom. The 150 sq ft room carries more of the lease than the 100 sq ft room, and the difference shows up every month.

All three add up to the same rent. The methods do not change what the landlord collects, and they do not change the total the household pays. They change who pays what. That is the part worth settling before the lease is signed rather than in month four, when one person has started counting the closet space.

The calculator on this page runs all three methods, adds utilities either way, and shows the result for each room, because a rent number alone rarely tells you what a roommate owes.

Even split versus square footage on the same $2,400 lease

Take a $2,400 lease with three bedrooms of 150, 120 and 100 sq ft, and four people: a couple in the 150 sq ft room and one person in each of the other two. The rent is fixed at $2,400 whichever method you pick, and the average per person is always $600. What moves is the split between the rooms.

Under the even per person method the couple pays $1,200 and each single pays $600. The couple has the largest room and two incomes against one, so this method asks the most from them and the least from the singles.

Even per room flips that. The couple pays $800 for the room, or $400 each, and each single pays $800 for a smaller room. The couple comes out $400 a month ahead of the singles while occupying the biggest bedroom, and that is usually the point where a house meeting happens.

The square footage method sits between the two. The couple pays $972.97 for the room, or $486.49 each, and the singles pay $778.38 and $648.65. The couple still pays more per room than anyone else because the room is the biggest, but less per person than the singles because two people are sharing it. Most households settle here, because it is the only one of the three that reacts to both the size of the room and the number of people in it.

Room by room: the three-person version of the same lease

Drop the couple and put one person in each bedroom and the arithmetic gets clean enough to check on paper. The three rooms total 370 sq ft, so the 150 sq ft room is 40.5% of the bedroom space, the 120 sq ft room is 32.4%, and the 100 sq ft room is 27.0%.

The person in the biggest room pays $324.32 more than the person in the smallest, which is $3,891.84 over a year. That gap is the whole reason the square footage method exists. In the same house under an even split, all three would pay $800 in rent and $100 in utilities, and the person in the 100 sq ft room would be paying the same as the person with 50% more space.

Notice that the rent column adds to exactly $2,400.00 even after rounding. When a split does not add up, it is almost always because each share was rounded and the pennies were dropped. The fix is to round two rooms down to the cent and give the leftover pennies to the largest share, so the total still matches the lease.

When a couple shares one bedroom

A couple in one bedroom is the case that breaks the simple formulas, and it is common enough that it deserves its own rule. Three things are true at once. The couple uses one bedroom, so they should not pay for two rooms. They use twice the hot water, twice the shelf space and twice the wear on the common areas, so they should not pay a single person's share either. And they usually have two incomes, which is why the conversation gets awkward.

The three methods produce three different answers for that couple on the $2,400 lease above:

• Even per person: $600 each, or $1,200 for the couple, against $600 for each single.
• Even per room: $400 each, or $800 for the couple, against $800 for each single.
• By square footage: $486.49 each, or $972.97 for the couple, against $778.38 and $648.65 for the singles.

The square footage number is the one most households can defend out loud, because it explains itself: the couple pays for the space they occupy, split between them, and the singles pay for theirs. A common alternative is to charge the couple a fixed premium over a single room, say an extra $100 to $150 a month, which covers the extra utility load without redoing the whole lease.

Utilities are a separate question, and there the fair answer is per person rather than per room. A $300 utility bill across four people is $75 each, and the couple pays $150 of it. That is not a penalty for being a couple. It is the cost of two people showering, doing laundry and charging phones.

Utilities: inside the rent or on top of it

Before you split anything, read the lease and find out what the rent already covers. A rent that includes heat and water is a different number from a rent that does not, and the difference can be $200 a month in a cold state. The most common arrangements are all-inclusive rent, rent plus tenant-paid electric and gas, and rent plus everything metered separately.

If utilities are included, split the rent and stop. If they are not, treat the utility total as a second pot and divide it per person, because usage scales with people rather than with bedrooms. The EIA monthly electricity price table puts the U.S. residential average near 17 cents per kilowatt hour in 2025, which is the figure behind the electricity line below. These are reasonable planning numbers for a three-bedroom apartment, and they are a starting point rather than a quote.

Two habits keep utility splits calm. Put the bill in one person's name and have the others transfer their share within three days of the due date, and share the actual bill image every month instead of a number someone typed. When a bill jumps by $80 in July, everyone can see the kilowatt hours and nobody has to take it on trust.

The room-size method, step by step

The square footage method has four steps, and the only one people get wrong is the first.

1. Measure each bedroom. Length times width, in feet, rounded to the nearest foot. A 12 by 12.5 room is 150 sq ft. Do not include closets unless one room has a walk-in and another has a shelf.
2. Add the bedrooms up. In the example above that is 370 sq ft. Only bedrooms count. Hallways, kitchen, living room and bathroom are shared by everyone, so they stay out of the calculation.
3. Divide each room by the total. 150 divided by 370 is 0.405, or 40.5%. Multiply by the rent to get that room's share.
4. Split each room among its occupants. A single pays the whole room share, a couple splits it in half, three people in one room split it three ways.

Leaving the common areas out is a choice, and it is worth saying so out loud. Some households allocate 10% to 20% of the rent to common space and divide that evenly, then apply square footage to the rest. It shifts maybe $40 a month between rooms in a typical apartment, and it makes the person in the smallest room feel better about the kitchen. Either version is fine as long as everyone agrees which one you are using before the first check is written.

What to put in writing before the first check

A split that lives only in a group chat will be relitigated. A one-page roommate agreement that covers six points prevents most of it, and it does not need a lawyer. The CFPB renting guide covers deposits and lease terms in plain language if you want a second opinion on any clause.

• Who is on the lease. Everyone who signs is liable to the landlord for the full rent, not just their share. If one person is not on the lease, the others are carrying that risk and should know it.
• Who pays whom, and when. One person collects and pays the landlord, or each pays the portal directly. Name the date, and name the late fee for missing it.
• The split itself. Write the percentage or the dollar figure for each room, plus the utility arrangement, and note the date it was agreed.
• The deposit. Who paid what into it, and how it comes back. Deposits are the single most common source of end-of-lease fights.
• Guests and sublets. How long a guest can stay before they count as an occupant, and whether a room can be sublet.
• Notice. How much warning someone gives before moving out, and what happens to their share if they leave mid-lease.

Keep the signed copy somewhere everyone can reach, and update it when the household changes. A split that was fair for three people is not automatically fair for four, and the person who moves in should get the same document the others signed.

When someone moves in or out mid-lease

Mid-month changes are where splits get messy, because rent is billed monthly and people move on the 12th. The clean fix is to prorate by days. Divide the monthly share by the number of days in that month, then multiply by the days the person was there.

Say the rent share is $800 and the move-out happens on the 21st of a 30-day month. The daily rate is $26.67, the person owes for 21 days, and that comes to $560.00. The remaining $240.00 belongs to whoever takes over the room, or to the household if the room sits empty. In a 31-day month the same 21 days cost $541.94, because the daily rate is lower.

Two details save trouble. Prorate the rent and the utilities on the same day count, so nobody pays a full utility share for half a month of showers. And settle the deposit separately from the monthly split, because a new roommate usually buys out the departing one's deposit rather than paying the landlord twice. If the landlord requires a new application, that has to happen before the move, not after.

Use the calculator above to rebuild the split the moment the household changes. Enter the new room sizes and occupant counts, and the per-room numbers update, which is faster than reopening the argument from scratch.