How the figures are worked out

Where the data comes from

Every sale is from HM Land Registry's Price Paid Data: residential sales in England and Wales since January 1995, with the price, date, address, type, tenure and whether the home was new. Sales reach the register up to six months after completion, so the latest months fill in over time. Each page says which monthly release its figures come from.

Floor areas come from the register of domestic Energy Performance Certificates kept by the Ministry of Housing, Communities and Local Government, which runs from 2008. Postcode geography is from the ONS Postcode Directory, exact positions from OS Open UPRN, today's values from the UK House Price Index and inflation from ONS CPIH. All are published under the Open Government Licence v3.0.

Matching a sale to its certificate

The register has no address reference number, so each sale is matched to a certificate by its address within the same postcode, in four tiers: the same number and flat; the same named building and flat; the only certificate in the postcode with that number; and a close match on the whole address. Checked against 2,222 pairs matched by hand, the first two tiers are right more than 99% of the time and the last two more than 96%.

A home with no matching certificate keeps its sold prices but has no floor area, no price per square metre and no implied range. Where the size comes from the certificate for the building, or from a close match, the page says so beside the floor area.

Price per square metre

The price paid divided by the floor area on the home's latest certificate, rounded to the nearest £10, and shown per square foot as well (one square metre is 10.7639 square feet). Older sales use today's measured area, so an extension built since then makes an old price look cheaper per metre than it was.

Today's value

The latest sale price indexed forward with the UK House Price Index for the home's council and type, falling back to the region's index and then the national one when a series is missing. It is an index, not a valuation: it knows nothing of improvements, condition or the market for that street.

Growth between sales

The compound annual rate from one sale of a home to the next, shown only when the sales are at least a year apart. After inflation divides out CPIH over the same months.

Area figures

Medians and quartiles of price per square metre over the last 24 months for every postcode, street, sector, district and council, from the sales we count: standard-price sales (category A, so not repossessions or transfers to companies), not three or more sales at one price on one day in a district, not type other, a price of £10,000 or more and a price per square metre between £200 and £40,000, matched in the first two tiers, or the third for houses. An area needs 12 counted sales for figures of its own; below that the page uses the sector, then the district, then the council, and names the area it uses.

The change on a year ago compares the median of the last 12 months with the 12 before, counting resales only, when both have 12 or more. New homes are left out of it because they reach the register months after they sell, so the latest months hold too few of them for a fair comparison; they still count in every other figure.

Implied range and the fair-value check

The implied range is the floor area multiplied by the sector's 25th and 75th percentile price per square metre: what homes that size sold for in the middle half of local sales.

The check divides an asking price by the floor area and compares the result with the sector's median for the same type of home when the sector has 12 or more such sales, otherwise the median of every type. More than 15% below the median is well below local sales, 5 to 15% below is below, within 5% either way is in line, 5 to 15% above is above, and more than 15% above is well above.

Rounding

Sold prices are shown as the register records them. Computed prices (today's value, ranges and medians) are rounded to the nearest £100 below £1m and the nearest £1,000 above; prices per square metre to £10; percentages to one decimal place; floor areas to the nearest square metre.

Corrections

We republish the registers rather than edit them. A wrong price or address is corrected through HM Land Registry, and a wrong certificate through the EPC register; corrections reach these pages with the next monthly load.

Not a valuation

An index-based comparison of sold prices, not a valuation. A surveyor's valuation looks at the home itself. Check an asking price or browse the areas.