Minor Dwelling / Granny Flat ROI Calculator

This calculator works out the return on building a minor dwelling or granny flat to rent out in New Zealand, showing the net annual rent, the gross and net yield, and how many years of rent it takes to pay back the build cost. Adding a small self-contained unit to a section you already own has become one of the most popular ways for homeowners to create income, and recent rule changes have made compact standalone dwellings easier to build in many areas. The appeal is the maths: because you are building on land you already have, the rent is measured against the build cost alone rather than the price of a whole property, which often produces a yield far higher than a standard rental. You enter the build cost, the weekly rent you expect, and the annual running costs such as extra rates, insurance and maintenance, and the calculator returns the net annual income, the gross yield against the build cost, the net yield after running costs, and the payback period in years. Use it to judge whether the build stacks up and to compare it against other uses of the money. Council rules on size, parking and services apply, and a minor dwelling can change your rates and insurance, so check those before committing. Estimate only, not financial advice.

Yields are against the build cost, not the whole property. Council rules, rates and insurance changes apply. Estimate only, not advice.