Minor Dwelling ROI Calculator

This calculator works out the likely return on building a minor dwelling, sleepout or granny flat to rent out, so you can judge whether the build stacks up financially before you commit. You enter three figures: the total build cost including consents and connections, the weekly rent you expect to charge, and the annual running costs such as rates, insurance, maintenance and management. From these it works out your net rent per year, the annual rent less running costs, and expresses that as a net rental yield on the build cost. It also shows the payback period, the years of net rent needed to recover what you spent on the build, and flags the added value potential from any lift in your property's overall worth, a benefit the yield figure does not capture. Use it to compare a minor dwelling against other uses of the same capital, such as a term deposit or another rental property, and to test how the return moves with different rent or running cost assumptions. Consent costs, connection fees and finishing standards vary widely between councils and builders, so get a firm quote before relying on the numbers. Rental income from a minor dwelling is taxable, so factor that into your real return. This is an indicative estimate only, not financial or building advice, and your actual costs and rent may differ.

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The yield is net rent over the build cost; the payback is how long the rent takes to recover the build cost, before any rise in your property value, which a minor dwelling can also add. Rental income is taxable. Estimate only, not financial advice.