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Flatmate Rent & Bills Splitter

Split rent and bills fairly between flatmates. Weight by room size, ensuite, and usage share. Generate a flatmate agreement summary.

By Konstantin IakovlevPublished 28 March 2026Last reviewed
Data stays on your deviceVerified formula

About this calculator

This calculator implements NZ flatmate cost sharing best practice from Tenancy Services NZ. Last consulted 18 May 2026. Verify the figures yourself by following the link.

NZ flatting cost benchmarks

Tenancy Services + Stats NZ 2026
  • •Median Auckland rent (3-bed): $720-820/wk
  • •Median Wellington rent (3-bed): $650-750/wk
  • •Median Christchurch rent (3-bed): $540-630/wk
  • •Typical shared bills: $100-180/wk (power+internet+water)
  • •Ensuite room weighting: +30% vs standard room
  • •Letting fees (banned 2018): Illegal — never pay these

Source: Tenancy Services NZ

Disclaimer

This calculator provides estimates for general information purposes only. Results are based on standard formulas and may not reflect your individual circumstances. Always consult a qualified professional for advice specific to your situation.

How fair flatmate splits are calculated

Two weights: rent by room (size + ensuite), bills by usage share. Each person gets their share of each.

  1. 1

    Room-weighted rent

    Rent_weight = rooms + (0.3 if ensuite)

    Bigger room + ensuite → larger share.

  2. 2

    Allocate rent

    Person_rent = weekly_rent × person_weight ÷ total_weights

    Sum of all weights = denominator.

  3. 3

    Usage-weighted bills

    Bill_weight = personal usage factor (1.0 = average, 2.0 = double, etc.)

    Heavy users (long showers, EV charging) take a larger share.

  4. 4

    Total per person

    Person_total = person_rent + person_bills

    Write into flatmate agreement.

Worked example

Inputs: Rent $850, bills $120, 3 people (one with ensuite)

Result: Ensuite person pays $850 × 1.3 ÷ 3.3 = $335 rent. Others $258 each. Bills $40 each.

Frequently Asked Questions

How should flatmates split bills fairly?
Common NZ approaches: (1) Even split — simple but unfair if rooms differ; (2) Per-room — multiply rent by room count; (3) Room-weighted — bigger room + ensuite pays more (the approach this calculator uses); (4) Usage-weighted bills — heavy power users pay more. Best practice is to agree upfront and write it into a flatmate agreement. Source: Tenancy Services.
Should partner stay-overs affect the bill split?
Common NZ flatting issue. RNZ reported flatmates often informally charge ~30-50% of one share when a partner stays 3+ nights/week. Or count the partner as a half-person in the split. This is a relationship issue more than a math one — agree upfront. Source: RNZ Lifestyle.
What's the maximum bond a NZ landlord can charge?
The maximum bond a NZ landlord can charge is 4 weeks' rent (Residential Tenancies Act 1986, s18). The bond must be lodged with Tenancy Services within 23 working days — landlords keeping it themselves is illegal. Letting fees (commission paid to property managers) have been banned since 12 December 2018, so don't pay one. At end of tenancy, the bond is refunded if the property is left clean and undamaged, or apportioned via the Tenancy Tribunal if there's a dispute. Source: Tenancy Services (tenancy.govt.nz).
How do flatmates usually split power and internet bills in NZ?
The most common NZ flat setup: one flatmate holds the account in their name (often the longest-staying or main lease-holder), and the others pay their share by bank transfer. The account holder is legally liable to the retailer for the full bill — so trust matters. To avoid disputes, set up a shared Splitwise/Pocketsmith group, or use a service like Sorted's bill splitter. Power bills are typically split evenly per person (or weighted by usage like EV charging or heaters). Internet is almost always split evenly since it's a fixed fee. Source: Sorted NZ (sorted.org.nz).

How this calculator works

This flatmate rent & bills splitter uses the latest data from official New Zealand government sources to provide accurate results. All calculations are performed in your browser — your data never leaves your device.

All calculations are performed in your browser — your data never leaves your device. Results are for general guidance only and should not be considered professional financial advice.

Built and maintained by Konstantin Iakovlev. Data sourced from the IRD and official New Zealand government sources.

Last reviewed:

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