How far a new home’s asking price sits above what similar homes nearby have sold for, with how sure the estimate is, or why there is no figure.
A new home often costs more than a similar second-hand home in the same area. That gap is the new build premium. Part of it reflects real value: the warranty, lower bills and a home with nothing worn out. Part of it is simply being new, and that part can fade once you have lived there and the home becomes a resale itself.
The tool sets a new home’s asking price against what similar homes nearby have sold for, moved to today’s prices, and says how sure the estimate is, or why there is none. It is an estimate from past sales nearby, never a valuation of the home.
The rules below are the ones in force, set by the backtest measured 1 Nov 2026.
Sources: HM Land Registry resales, with EPC floor areas, via HomePortfolio (Open Government Licence v3.0); HomePortfolio new-build listings (Facts the builder publishes). Contains HM Land Registry data © Crown copyright and database right 2026. Contains public sector information licensed under the Open Government Licence v3.0.
Illustration, not advice: an estimate from past sales nearby, never a valuation of this home. No lender or product is named or recommended.
Each estimate is labelled by its evidence: how many sales matched, how far apart their prices per square metre are (the spread between the quartiles, against the middle), and how old the middle sale is. The limits are the backtest’s, set so each label held to its measured error.
| Confidence | Matched sales | Spread within | Middle sale at most |
|---|---|---|---|
| High | 5 or more | 35% | 36 months old |
| Low | 5 or more | 100% | 36 months old |
Evidence thinner, more spread out or older than the loosest limit gets no figure: the tool says which limit it missed instead. A Low estimate is shown only as its range, with the reason it is low, never as one figure.
A home whose builder publishes no floor area is matched on type and bedrooms alone, and its estimate is at most Low.
Measured on 3,351 resales across 80 neighbourhoods of new-build developments in 10 regions, sold from 1 Aug 2025 to 31 Jul 2026: each valued from the sales before it, as a new home would be, and checked against the price it really sold for.
High estimates were a median 10% from the real price, held to 10%, on 2,936 sales.
Low estimates were a median 17.1% from the real price, held to 20%, on 303 sales.
The method gave no figure for 3.3% of the sales it was tested on: evidence it could not hold to its error.
| Region | Resales tested | Estimated | Median error |
|---|---|---|---|
| East Midlands | 349 | 330 | 9.7% |
| East of England | 285 | 275 | 9.1% |
| London | 427 | 423 | 11.3% |
| North East | 311 | 305 | 11% |
| North West | 358 | 352 | 11.5% |
| South East | 355 | 344 | 10% |
| South West | 376 | 359 | 8.3% |
| Wales | 356 | 345 | 11.5% |
| West Midlands | 322 | 308 | 9.2% |
| Yorkshire and The Humber | 212 | 198 | 14.1% |
| England and Wales | 3,351 | 3,239 | 10.5% |
How much more a new home asks than similar second-hand homes nearby have sold for. Part of it reflects the warranty, lower bills and a home with nothing worn out; part of it is simply being new.
Part of the price pays for real value: a structural warranty, usually for 10 years, a better energy rating and a home with nothing worn out. Part is simply being new, and that part can fade once the home is a resale.
The part of the price that reflects being brand new can fade once the home becomes a second-hand one. How much depends on the price you paid against similar local homes and on the local market, so compare before you buy.
From resales of homes of the same type nearby, with bedrooms within 1 and a floor area within 25%, sold within 36 months and moved to today’s prices. Their prices per square metre at the new home’s floor area give a range; the premium is the asking price against its middle.
Too few similar homes have sold nearby, their prices are too spread out, the sales are too old, or the builder publishes no floor area. Rather than guess, the tool says which.
Not by itself. It is the gap to similar resales nearby, an estimate from past sales and never a valuation. Some of the gap can be worth paying for; use it to ask questions and to negotiate.
Lenders normally lend on the lower of the price you agreed and their own valuation, so a valuation below the price means a smaller loan or a bigger deposit.
Sources: resale prices from HM Land Registry Price Paid Data via HomePortfolio (HM Land Registry data, Crown copyright, Open Government Licence), moved to today with HomePortfolio’s repeat-sales index; floor areas from energy certificates; energy ratings from the government’s energy performance statistics.