How do you split rent fairly between flatmates?

Common rules are equal shares, shares by room area or shares by income. For a ₹54,000 flat with rooms of 180, 140 and 120 sq ft, equal is ₹18,000 each while area-based shares are ₹22,091, ₹17,182 and ₹14,727. Fair depends on what your group values, so agree the rule before signing.

How do flatmates split electricity bills?

A simple method is by days present: divide the bill by total person-days and multiply by each person's days. A ₹3,600 bill over 75 person-days is ₹48 per day. Some flatmates charge the person with an air conditioner a larger share or a fixed extra amount. Agree it in advance.

How should flatmates split the security deposit?

Record who paid how much on the day, and use the same proportion for the refund. If the lease is in one name, the others have no direct claim on the landlord, so a signed note or message among flatmates is worth having. Check your state's rent law and the agreement for timing and deductions.

What happens to the deposit when a flatmate leaves?

It depends on what you agreed. A common arrangement is that the incoming person pays the leaving person their deposit share directly, and the landlord's deposit stays unchanged. Write down the amount, the date and who is responsible for the replacement, and tell the landlord if the lease is affected.

How do we avoid arguments when settling bills?

Record every shared expense with the date, who paid and the shares. Settle on a fixed day each month with one transfer per person, round to the nearest rupee and keep a running balance of who owes whom. Most disputes come from forgotten items and unclear rules, not from the maths.

Split Rent With Flatmates: Methods and Maths

What are the common ways to split rent?

There are four rules most flatmates choose from, and every one is defensible. They differ in what they treat as fair.

Rule	How it works	Fits when	What it overlooks
Equal	Total rent ÷ number of people	Rooms and incomes are similar	A big gap in room size or income
By room area	Share = room area ÷ total area × rent	Rooms differ in size	Attached bathrooms, balconies and light
By income	Share = income ÷ total income × rent	Incomes differ widely	Whether people choose the same flat
Hybrid	Part equal, part by room or income	A compromise is wanted	It is harder to explain

There is no right answer in general. The useful move is to agree a rule while everyone still has a choice about taking the flat.

How do the shares work out? A worked flat

Say three flatmates, Aman, Bela and Chirag, take a 3BHK in Bengaluru for ₹54,000 a month. Room sizes are 180 sq ft (master with attached bathroom), 140 sq ft and 120 sq ft. Monthly take-home pay is ₹1,20,000, ₹80,000 and ₹60,000.

Equal. ₹54,000 ÷ 3 = ₹18,000 each.

By room area. Total area = 180 + 140 + 120 = 440 sq ft.

Aman: 180 ÷ 440 × 54,000 = ₹22,090.91, shown as ₹22,091
Bela: 140 ÷ 440 × 54,000 = ₹17,181.82, shown as ₹17,182
Chirag: 120 ÷ 440 × 54,000 = ₹14,727.27, shown as ₹14,727
Check: 22,091 + 17,182 + 14,727 = ₹54,000

By income. Total income = 1,20,000 + 80,000 + 60,000 = ₹2,60,000.

Aman: 1,20,000 ÷ 2,60,000 × 54,000 = ₹24,923.08, shown as ₹24,923
Bela: 80,000 ÷ 2,60,000 × 54,000 = ₹16,615.38, shown as ₹16,615
Chirag: 60,000 ÷ 2,60,000 × 54,000 = ₹12,461.54, shown as ₹12,462
Check: 24,923 + 16,615 + 12,462 = ₹54,000 (rounded so the total matches)

Person	Equal (₹)	By area (₹)	By income (₹)
Aman	18,000	22,091	24,923
Bela	18,000	17,182	16,615
Chirag	18,000	14,727	12,462

Chirag pays ₹5,538 a month less under the income rule than under the equal rule (18,000 - 12,462). Aman pays ₹6,923 more (24,923 - 18,000). Same flat, very different bills. This is why the choice is worth a short conversation.

How should I split bills that change every month?

Electricity, water, gas, internet, the maid and the cook behave differently from rent. Some are fixed, some are not.

Fixed and shared by everyone (internet, maid, gas): equal shares, or equal among those who use it.
Variable by usage (electricity): by days present, or by room if rooms have their own meter or AC.
Individual (a personal subscription): the person who uses it pays.

Example by days present. The electricity bill is ₹3,600. Aman and Bela were in the flat for 30 days each. Chirag was away for half the month and was there for 15 days. Total person-days = 30 + 30 + 15 = 75.

Cost per person-day = ₹3,600 ÷ 75 = ₹48

Aman: 30 × 48 = ₹1,440
Bela: 30 × 48 = ₹1,440
Chirag: 15 × 48 = ₹720
Check: 1,440 + 1,440 + 720 = ₹3,600

An air conditioner in one room can change this. Flatmates sometimes agree that the person with the AC pays a larger share of electricity, or a fixed extra amount.

What about the security deposit?

The deposit is usually paid to the landlord in one name, but everyone contributes. A few habits keep it fair:

Record who paid how much on the day of payment. If rent is split by area, many flatmates also split the deposit in the same proportion. Whatever rule is chosen, write it down.
If the lease is in one person's name, the others do not have a direct claim on the landlord. A short signed note or message among flatmates stating each person's contribution and how refunds are shared protects everyone.
When someone leaves and someone new joins, the new person's deposit goes to the person leaving, not to the landlord, unless the landlord is also involved in the change.
Photograph the flat on move-in so that deductions at the end can be checked against the inventory.

Deposit rules and timelines depend on your state's rent law and the agreement you sign. Check your agreement and local rules.

How do we settle without an argument?

Most disputes are not about the maths. They are about remembering, timing and tone.

Pick one person to pay each shared bill, or rotate the role each month.
Record every shared expense with the date, amount and who paid.
Settle on a fixed day, for example the 5th. One UPI transfer per person is enough.
Round to the nearest rupee and agree who absorbs the rounding.
Keep a running total of who owes whom, so that small amounts are not forgotten.

If someone is late with a payment, a calm message with the number and the reason is better than silence. If someone leaves, settle bills up to their last day and return the deposit share as agreed in writing.

What do flatmates miss?

Agreeing a rule only after the first bill. By then each person has already formed an opinion.
Ignoring exit costs. Notice period, who finds the replacement and who pays the vacant month.
Treating groceries like rent. Shared groceries and personal food are different. Agree which is which.
Letting one person carry the platform. If the lease, the Wi-Fi and the maid are all in one name, that person takes the risk when someone leaves unpaid.
No record. Without a list, "I paid last time" cannot be checked.
Forgetting festival and maintenance one-offs. Society charges and repairs need a rule too.

What if someone's circumstances change mid-lease?

A fixed rule is easiest when nothing changes. In reality, someone gets a raise, works from home more, or leaves for a new job. Agree early how the group handles three common changes.

Rent rises at renewal. Many tenancies raise rent at renewal. Decide whether the increase is split in the same proportion as the existing rent or equally, and write it down when the lease is renewed.
A flatmate leaves. Decide who finds the replacement, how long the leaving person pays while the room is empty and what the notice period is. If the leaving person pays until a replacement moves in, set a maximum number of weeks.
A new flatmate joins. The new person takes the room's existing share unless the group agrees to recalculate. If the group recalculates by area or income, everyone's share changes, so the group should agree the new figures before the person moves in.

Whichever way you decide, keep the old numbers and the new numbers in the same list with dates, so that anyone can see when a rule changed and why.

What to check for your own situation

Which rule do we use for rent, and which for variable bills?
Is the rule written down where everyone can see it?
Who paid how much of the deposit, and how is it returned?
What is the notice period if someone leaves?
When do we settle each month?

How this looks in Kubear

Kubear is a web app with Personal and Household spaces and shared expense splits. You can record a shared expense, say who paid and set the shares, then see who owes whom. Each entry is reviewed and confirmed before it is saved. Kubear shows the numbers and the working. It does not tell flatmates which rule to use.

This is general education, not personal financial, tax or insurance advice.

How to Split Rent and Bills With Flatmates: Methods and the Maths