All calculators are downloadable Excel spreadsheets that allow you to save and amend your own personal data.With this spreadsheet, enter your personal data in the purple coloured cells.
How much house can I afford calculator
This calculator is for those who are looking at buying a house and wondering what is the most they could pay for a house.
You just need to enter what is the most you could possibly pay in rent per year and still be OK financially. If you already own a home and are looking to upsize, then in cell C11, just enter the highest amount per year you could possibly spend on a mortgage. You will also need to enter some estimates around expected costs of the new house, and some mortgage assumptions.
From there, you can see how much house you could likely afford, what your annual home ownership costs may be, and what percentage of your income those costs make up.
When buying a house, ideally you don’t want to buy at this maximum level you can afford. You’d want to leave a bit of wriggle room should things not pan out as expected. Having some extra money saved even after the downpayment is made will help. As will an emergency fund and adequate insurance. Job security is also an important consideration. Every situation is personal, and the the better your planning is and the more you have done to minimise risk, the more comfortable you may be buying close to your limit.
Housing affordability data
This is more data than calculator. What it shows is historical housing affordability since 2017 in 10 different regions, plus the nationwide average.
The affordability data it provides includes:
Monthly mortgage repayments over time
Assuming a 20% deposit, how large your deposit needs to be over time
How much deposit is required as a percentage of income over time
How much housing costs relative to income over time
How much monthly mortgage repayments are as a percentage of income over time
There is even a section (cells I2 to I5) where you can enter your personal information for a house you may be looking at to see how affordable the property is with your own personal numbers and how that level of affordability compares to the most recent years data for your area.
A bit of information on the data:
2017 is the first year in the data as that is the first year that data is available for ‘special’ mortgage interest rates. Although they are called special, they are not that unique. Most homeowners have more than 20% equity and are eligible for special interest rates, so I thought it best to use these interest rates since they are the most common. If you aren’t eligible for special interest rates, your results will be a bit worse than the calculator assumes.
Median income data for 2025 won’t be available until mid 2026. That means house price, house deposit and mortgage repayments as a percentage of gross income are not available for 2025 yet. I will update the calculator annually as the information is made public mid year.
For the house price data I have used median house price values rather than average and I have selected August as the month to use for year on year comparison.
For the mortgage interest rate I have used the 1 year special interest rate as that is often the most attractive. Again, I have used August as the selected month for year on year comparison.
For the affordability results I have assumed a 20% deposit and a 30 year mortgage. If you decrease or increase either, the results would be worse or better respectively. The calculator doesn’t allow for a change to these assumptions as affordability over time needs to be measured consistently in the same way. For more personalised results, refer to the first calculator on this page.
Unfortunately gross income is used. Most of us are more interested in what affordability is relative to our take home income is. But doing so would mean you can’t compare to previous years data as each years tax take is unknown because we don’t know if your income is individual or household or business etc. Gross is the simplest and cleanest way to compare across periods. Again, for more personalised results, check out the first calculator on this page.
Monthly repayments (column B) and deposit required (column E) don’t tell us much on their own. Of course they will increase over time as house prices increase over a long enough timeframe. But they do let us know how much we will need right now. But this is why I haven’t included these in the graphs. However, the house price, house deposit and mortgage repayments as a percentage of income have all been included in graph form, as they can be compared across the ages. This is because house prices and income are both adjusted for inflation.
Unfortunately I have not been able to include Gisborne, Hawkes Bay, Nelson, Tasman, Marlborough and West Coast in the regional data. For income data, Statistics NZ groups Gisborne with Hawkes Bay, and Tasman with Nelson, Marlborough and West Coast, but real estate data does not group the regions in the same way. For these areas you may be able to get a sense of the results by comparing to regions that may be similar.
For 2017 and 2018, Statistics NZ did not break down annual income by region (other than Auckland, Wellington and Christchurch). So for the remaining regions for those two years, I used the average discrepancy between the region and the national average to determine those years median income.
For personalised advice on deciding whether or not buying a property should be part of your financial plan, then get in touch for a no obligations chat to see how we may be able to add value for you.
For more calculators, click here