Housing
New Zealand's house price index (2015=100) explained
What an index at 167 means, how the OECD-sourced house-price series works, and what the price-to-income ratio does and does not tell you.
An index at 167 — New Zealand's house price index (2015 = 100) as Younivi republishes it — means residential prices are about two-thirds higher than in 2015 on average, even with recent year-over-year change slightly negative. This note explains how the index is built, what the level and the price-to-income ratio do and do not tell you, and where the sensible reading limits lie.
The figures here come from the house-price series Younivi republishes on the House Price desk: an international residential property price index collection with the OECD among its sources, plus a derived year-over-year change series and a price-to-income ratio series. The producing agencies are cited on the desk; Younivi computes only the labelled derived figures.
What "2015 = 100" means
A property price index does not track individual houses; it tracks the market-wide trend in residential prices after controlling, so far as methodology allows, for changes in the mix of what is sold. If the index reads 100 in 2015 and 167 in December 2025, the interpretation is: the average price of the same underlying market rose by about 67% over that period. Households do not experience this as a 67% rise in their own home's value — the true average is a statistical construction — but the direction and rough magnitude are the facts the series is designed to convey.
An index level out of context is just a reference: choose 2015 as the base and 167 is the level; choose another base and the number changes arbitrarily. That is why the sensible reading of any single index is the year-over-year change, which the desk reports as a derived figure: for December 2025, New Zealand shows −1.22% year over year, computed from the published index. "Derived" means our arithmetic: we take the official levels a year apart and compute the percentage difference. The precise change on an official basis may differ slightly where the source publishes its own growth series with different rounding or weight dating.
The level and the change, together
| Measure | Dec 2025 value | Kind |
|---|---|---|
| House price index (2015 = 100) | 167.06 | Official level (republished) |
| Year-over-year change | −1.22% | Derived from the index |
| Price-to-income ratio | 101.3 | Derived ratio |
Read together, these three numbers describe a market that has risen markedly since mid-2010s reference, is easing slightly year over year, and remains expensive relative to household incomes. The same three measures exist for the other economies on the desk, so these are comparable across countries on the desk's own terms.
Why the price-to-income ratio matters
The price-to-income series compares house prices with household income. A value over 100 — as New Zealand's 101.3 read at end-2025 — means prices average at or above the ratio's reference scale; what matters more is the position relative to other economies and to the same economy's history. The ratio is a stress gauge: it moves when prices move (as in 2020–2023, when many economies' ratios surged) and when incomes move (faster wage growth lowers the ratio without any price fall).
Its limits are equally worth naming. It uses average incomes, so it is blind to distribution: a market can be affordable for top earners and unaffordable for median ones. It does not include borrowing costs — an era of cheap mortgage finance can send prices high while the ratio's income denominator keeps the number looking stable. And it is a ratio of averages, so a crash in one region and boom in another can net to a quiet headline.
Cross-country comparisons: what differs
The desk publishes the index and year-over-year change for many economies, with recent extremes found at both ends of the published sample — Türkiye's index near 2,763 in mid-2026 leads the listed sample of the republished file, with Hungary at 380.6 on a slightly earlier date. Causes of such big cross-country gaps are structural: long inflation histories compound into high index levels (Türkiye's is extreme on any base), tax rules and mortgage markets change who can finance what, and statistical agencies build their series from different administrative universes. So a country-to-country level comparison tells you less about affordability than the year-over-year change or the price-to-income ratio, which are built to cancel some of these differences.
What an index can and cannot say about your street
A national index averages enormous internal variation. Regional, weather, zoning and school-related factors re-price individual streets around the average; the index deliberately nets them out. If a reader's question is "what is my house worth now?", the index answers vaguely — direction and rough national magnitude — and a valuation sits outside our remit and outside what any index can honestly provide.
Timing is a second limit. This series is compiled and periodically revised by its sources; the December-2025 figure is the latest in the file Younivi republishes, with later observations lagging. Markets can move between release dates, especially in currencies or credit conditions that the index only captures with a delay.
Where this fits in the wider picture
House price indexes are national aggregates, and it is worth being explicit about what that means for a country like New Zealand. The index is not a single city's market; it is a national construction that averages prices across regions with very different dynamics. A period of strength in one metropolitan area and weakness elsewhere can produce a modest national number, just as a broad-based rise can look like a city story when the largest market dominates the weighting. The aggregate is deliberately designed to net these differences out, which is its strength and also its limit for any reader asking about a particular place.
The 2015=100 convention is what makes cross-country reading possible. Each country's series is expressed relative to the same reference year, so the index level answers a common question: how far have prices moved since 2015 in this economy? Choosing a shared base does not erase differences in methodology, coverage or the mix of dwellings, and it does not make one level directly comparable to another as a price. It does mean that the movement from the base is expressed on a common scale, which is what a reader needs for an international view.
Read in that frame, the index is best understood as a comparable trend measure: useful for direction, magnitude since a common reference, and cross-country context, and silent on the value of any individual home.
How to read this on Younivi
The HPI page on the House Price desk shows New Zealand alongside other economies with the full history, and the desk's other pages cover the derived year-over-year change and the price-to-income ratio with source citations. Figures are republished official data, may lag the producer, and this is not financial advice on any property decision.