Where our information comes from

Our house price and property information comes from our lending for owner-occupier houses.

As one of the UK’s biggest mortgage providers, that’s a lot of information. In fact, our house price data stretches all the way back to 1952, which is the longest unbroken run of data available.

How we calculate the house prices

Our house prices are mix adjusted. This means that we track a representative house over time, fixing the relative weight given to each property characteristic, such as the type of property or number of bedrooms.

This stops results being distorted due to changes in the mixture of properties sold month to month. It also means we can:

  • Focus on the underlying trends in property values.

  • Estimate the cost of a house with a given set of characteristics.

  • Create the ‘typical’ UK house and track its value over time.

Full details of our house price index

For full details of our index, download our house price index methodology.

Why our house price index may be different to Halifax’s

For long periods of time our house prices follow similar patterns. This is because we use similar techniques to produce prices.

The average price differs because the representative properties we track are slightly different.

Seasonal adjustments to our monthly index

House prices are slightly seasonal. They’re higher at certain times of year regardless of the overall trend. This tends to be in spring and summer, when more buyers are in the market.

We adjust our monthly index seasonally to remove this effect. As a result we can report month-on-month changes that better reflect the overall trend in prices.

Our sample size

The exact sample size will depend on the number of mortgages we offer. So, the sizes vary from month to month. However, as one of the UK’s largest mortgage lenders, we’re confident we can produce a representative house price series.

When the index is published

The monthly index is published within a few days either side of the last day of the month. The quarterly indices are updated at the same time, at the end of each quarter.

Making a complaint about the house price index

If you have a complaint about the house price index, please see our complaints page for information about how to contact us.

How the IOSCO Principles apply to the index

Please download our statement regarding IOSCO (International Organization of Securities Commissions) Principles.

Legal information

The Nationwide House Price Indices (NHPI) are prepared from information that we believe is collated with care, but no representation is made as to their accuracy or completeness. We reserve the right to vary our methodology and to edit or discontinue the indices at any time, for regulatory or other reasons.

Persons seeking to place reliance on the indices for any purpose whatsoever do so at their own risk and should be aware that various factors, including external factors beyond Nationwide Building Society’s control might necessitate material changes to the indices.

The NHPI may not be used for commercial purposes, including as a reference for:

1) determining the interest payable, or other sums due, under loan agreements or other contracts relating to investments
2) determining the price at which investments may be bought or sold or the value of investments, or
3) measuring the performance of investments.


Nationwide Building Society is the owner of the trade mark “Nationwide” and all copyright and other rights in the NHPI.

The application of the IOSCO Principles on financial benchmarks to the NHPI is more fully set out in our statement regarding IOSCO Principles - PDF, 260KB (opens in a new window).

Nationwide considers that its arrangements for administration of the NHPI comply with the IOSCO Principles in a proportionate manner having regard to the nature of the index.

Commentary and other materials posted on our website are not intended to amount to advice on which reliance should be placed or an offer to sell or solicit the purchase by you of any products or services that we provide.

We therefore do not accept any liability or responsibility arising from any reliance placed on such materials by any visitor to our website, or by anyone who may be informed of any of its contents.