What is the most accurate UK house price index?

The UK House Price Index from HM Land Registry is the most complete, because it is built from actual completed sales including cash purchases. Its trade-off is timing: completions are registered weeks after agreement, so it describes the market as it was roughly two to three months ago and early figures are revised.

Why do Halifax and Nationwide house price figures differ?

Each index is built from that lender's own mortgage approvals. Different customer bases, regional footprints and seasonal adjustment methods produce different monthly figures, and neither includes cash buyers, who account for roughly a third of UK transactions.

Are Rightmove house prices accurate?

Rightmove publishes asking prices of newly listed properties, not sale prices. It is the earliest signal in the chain and useful for gauging seller confidence, but actual sold prices typically settle below asking, with the gap widening in weak markets.

Where does UK rental data come from?

The Office for National Statistics publishes the Price Index of Private Rents (PIPR) monthly, built from a large sample of actual rental records across the UK. Portal-listed rents run ahead of it because they capture new lets only, while PIPR includes existing tenancies.

What data does Clarity use?

Clarity's area scores are built from official sources, principally HM Land Registry sold price data and ONS rental and demographic statistics, refreshed monthly through our data pipeline and combined into yield, growth and tenant demand scores for 977 UK areas.

Where UK house price data comes from

Five well-known sources publish five different numbers for the same market. What each one measures and how to read them together.

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UK house price sources disagree because they measure different moments in the same transaction. Rightmove records asking prices at listing, Halifax and Nationwide record mortgage approvals, and the Land Registry's UK House Price Index records completed sales, including cash buyers. The Land Registry is the most accurate but the slowest; the others trade completeness for speed.

One sale, four measurement points

A typical English purchase takes four to six months from listing to registration. The price is first visible as an asking price, then as a mortgage approval value, then as a completed sale, and finally as a registered transaction at the Land Registry. Each public index samples one of those points, which is why they appear to contradict each other while describing the same market. When conditions turn, the asking-price indices move first, the lender indices follow within a couple of months, and the official index confirms the move a quarter later.

The five sources, compared

Main UK house price sources
Source	Measures	Lag	Blind spots
UK HPI (Land Registry/ONS)	Completed, registered sales	2 to 3 months, revised	Slow; early months understated
Nationwide HPI	Own mortgage approvals	Same month	No cash buyers; one lender's book
Halifax HPI	Own mortgage approvals	Same month	No cash buyers; one lender's book
Rightmove HPI	Asking prices at listing	Leads the market	Sellers' hopes, not outcomes
RICS survey	Surveyor sentiment balance	Same month	Direction only, no price level

Cash purchases are roughly a third of UK transactions and appear only in the UK HPI.

The practical conclusion: never compare a number from one source with last month's number from another. Pick the official index for levels and long-run trends, and use the faster series only for direction.

Rental data: PIPR and the portals

On the rental side the official series is the ONS Price Index of Private Rents, published monthly from a large sample of actual tenancy records. It includes existing tenancies, so it moves more slowly than the rents you see advertised: portal listings capture new lets only, which re-price immediately, while sitting tenants re-price at renewal. For underwriting a purchase, advertised rents for comparable properties tell you what you can charge a new tenant; PIPR tells you how the whole market is trending and is the better series for judging an area's rent growth.

A working method for investors

How to read the sources together

Use the UK HPI for area-level price levels, yields and 12 month trends; it is the only series built from every completed sale.
Watch Rightmove and the lender indices for turning points, since they lead the official series by one to three months.
Treat any single month's print as noise; three-month trends carry the signal.
Compare a specific property against Land Registry sold prices for the same street or postcode district, not against an index.
Check rent assumptions against both advertised lets and PIPR; if the two diverge sharply, the advertised figure is usually about to correct.

How Clarity uses this data

The scores in the Clarity Investment Map are built on the slow, accurate end of the chain: HM Land Registry sold prices and ONS rental and demographic statistics, ingested through our pipeline and refreshed monthly. Entry prices and 12 month growth come from registered transactions, rents from official series sense-checked against live listings, and tenant demand from a combination of demographic and market activity signals. We publish the method openly because trusting an area score requires knowing what is underneath it; the same numbers feed the monthly PDF report for each matched area.

Frequently asked questions

What is the most accurate UK house price index?: The UK House Price Index from HM Land Registry is the most complete, because it is built from actual completed sales including cash purchases. Its trade-off is timing: completions are registered weeks after agreement, so it describes the market as it was roughly two to three months ago and early figures are revised.
Why do Halifax and Nationwide house price figures differ?: Each index is built from that lender's own mortgage approvals. Different customer bases, regional footprints and seasonal adjustment methods produce different monthly figures, and neither includes cash buyers, who account for roughly a third of UK transactions.
Are Rightmove house prices accurate?: Rightmove publishes asking prices of newly listed properties, not sale prices. It is the earliest signal in the chain and useful for gauging seller confidence, but actual sold prices typically settle below asking, with the gap widening in weak markets.
Where does UK rental data come from?: The Office for National Statistics publishes the Price Index of Private Rents (PIPR) monthly, built from a large sample of actual rental records across the UK. Portal-listed rents run ahead of it because they capture new lets only, while PIPR includes existing tenancies.
What data does Clarity use?: Clarity's area scores are built from official sources, principally HM Land Registry sold price data and ONS rental and demographic statistics, refreshed monthly through our data pipeline and combined into yield, growth and tenant demand scores for 977 UK areas.

Sources and further reading

Written by the Clarity Property Investments research team. Last reviewed 12 June 2026. This article is general information, not financial or tax advice.