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How to split rent fairly by room size (and split the bills)
Splitting rent equally feels fair until one person has the big room with the ensuite. Here's a simple method housemates can agree on, plus a fair way to split the bills.
Step 1: split common space evenly
Decide what share of the rent pays for common areas (kitchen, living room, bathrooms everyone uses). Split that part evenly per person. Couples sharing a room count as two people for this part.
Step 2: split private space by size and extras
Split the rest by each bedroom's floor area, then add a weighting for extras like an ensuite, a balcony or a car space. Agree on those weightings before anyone sees the final numbers.
| Simple example (illustration) | |
|---|---|
| Weekly rent | $900 |
| Common share (40%) | $360 ÷ 3 people = $120 each |
| Private share (60%) | $540 split by room size: 15 m², 12 m², 9 m² |
| Result | $345, $300 and $255 (adds up to $900) |
Bills: supply charge evenly, usage by days at home
Most power and gas bills have a daily supply charge and a usage charge. Split the supply charge evenly between everyone on the lease, and the usage by the number of days each person was actually living there. That handles someone moving in or out mid-bill.
Rent increases
Rules on how often and with how much notice rent can go up differ by state. In NSW, for example, rent increases are now limited to once a year for all lease types (NSW changes to rental laws). Check your state's body: NSW, VIC, QLD, WA, SA, TAS, ACT, NT.
Want it done for you? Fair Rent & Bills Splitter + Rent Increase Check (AU)
An offline tool that splits rent by room size, ensuite and parking (always adding up to the exact rent), splits bills by days at home, and checks a rent increase with a polite email to your agent.
- Rent per week, fortnight and month
- Bills split: supply charge evenly, usage by days at home
- Rent increase check with a flag for short notice
- Works offline; your data stays on your device
US$5.99 one-time on Whop. Instant download.
See it on Whop →Related guides
- NSW rental application: what to prepare (and what to keep private)
- Rental inspection checklist: room-by-room checks to protect your bond
- Australian budget planner: start from your real take-home pay
General information only, not legal or financial advice. The example figures are made up. Tenancy rules differ by state, so check your state's official page. Last checked 16 Nov 2026.