How our estimates work
The data behind the number, and the limits you should know about.
Where we are today
Houseprice.io is in beta. Right now the estimate you see is illustrative: it uses the property type and number of bedrooms to produce a typical figure, and the comparable sales shown are examples of the kind of evidence a full estimate uses. We label this clearly on every result. We're connecting a property data provider so estimates and comparables are based on real sales for your address, and this page will be updated when that happens.
How a full automated estimate works
An automated valuation model (AVM) predicts what a home would sell for by learning from homes that have already sold. In England and Wales, every residential sale registered with HM Land Registry is published in its Price Paid Data, going back to 1995. Scotland and Northern Ireland have their own registers. These records give the price, date, postcode and whether the home is detached, semi-detached, terraced or a flat.
On its own, a sale price says little about size or quality, so a good model adds other public and commercial data:
- Energy Performance Certificates, which record floor area, the number of habitable rooms and energy rating for most homes sold or let since 2008.
- Location features such as distance to stations and schools, and local price trends.
- Market movement since each comparable sold, so a sale from three years ago is adjusted to today's market.
The model weighs recent sales of similar homes close by most heavily. Where there are plenty of those, the estimate is tighter. Where homes rarely sell, or every house is different, the range widens.
Why we show a range
A single figure looks precise but isn't. Our range reflects how closely similar homes nearby have sold to each other. If your home has had major work done, or has problems a buyer would notice, its real value can sit outside the range.
What an estimate can't see
- Condition, decoration and recent improvements such as a new kitchen, bathroom or extension
- Unregistered changes: a loft conversion that isn't on the EPC yet, or a garage turned into a room
- Problems like subsidence, damp, short leases or high service charges on flats
- Street-level detail: a busy road, a view, or which side of a catchment boundary you're on
What it isn't
Our estimates are not a RICS Red Book valuation, a mortgage valuation or a survey. Lenders, solicitors and courts won't accept them, and you shouldn't rely on them for financial or legal decisions. For an opinion based on your actual home, ask a local estate agent or a RICS-registered valuer.
Data and licences
Once live, estimates will use data that includes HM Land Registry data © Crown copyright and database right, licensed under the Open Government Licence v3.0, alongside data from our property data supplier.
Want to go deeper? Read how house prices are estimated and understanding comparable sales.