Granny Flat Cash Flow Calculator

Granny flat cash flow calculator

For investors and homeowners: see the flat's own cash flow, your usable equity, and the whole property's position before and after.

Rent & build

Suburb (optional, pre-fills suggested rents)

Indicative median rents, source: Queensland RTA bond statistics, Sep quarter 2026 (published Oct 2026) - check with a local property manager. New self-contained granny flats and units generally rent above the RTA median for older units, so per-unit rents are set within planning ranges ($380-$450 studio/1 bed, $450-$520 2 bed).

Main house rent ($/wk)

New dwelling rent per unit ($/wk)

Number of rental units

Utilities included (internet, power, water)

Utilities rent premium ($/wk per unit)

Owner utilities cost, estimate ($/wk per unit)

Solar on site

Utilities cut with solar only (%, estimate)

Utilities cut with solar + battery (%, estimate)

Model

Package

Build price ($, editable)

Your loan & costs

Cash / deposit contribution ($)

Loan amount ($, auto)

Interest rate (%)

Loan term (years)

Repayment type

Vacancy (weeks/yr)

Insurance ($/yr)

Extra council & water rates ($/yr)

Property management (% of rent)

Maintenance ($/yr)

Whole property

Property value ($)

Current mortgage owing ($)

Current repayments ($, blank = calculate)

Repayment frequency

Existing loan rate (%)

Existing loan years remaining

Max LVR (%)

Estimate only, not financial or lending advice. Figures are indicative; speak to a licensed broker/adviser and your accountant. Rents, rates and costs vary by property.

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