Because each one uses a different basis and a different sample, and almost none of them tell you which. Same house, same public data, three answers — the difference is method, not secret knowledge.
buying
Why property sites disagree about what the same house is worth
Because each one uses a different basis and a different sample, and almost none of them tell you which.
- 1 min read
- Updated 21 September 2026
Part 1 of 4
What makes two estimates differ
| Choice the model makes | Effect on the number |
|---|---|
| Geography used (street, postcode, sector, district) | A wider net means more sales but less relevance |
| Time window (12 months vs 5 years) | Longer windows smooth trends but drag in stale prices |
| Whether flats and houses are mixed | Mixing can move a median a long way |
| Whether prices are index-adjusted to today | An unadjusted 2021 sale understates today's market |
| Sample size behind the figure | Six sales and six hundred deserve different confidence |
The question worth asking any estimate is simply: how many sales is this based on, over what area and what period? A figure that will not tell you cannot be argued with, which is not the same as being right.
Our own estimate shows a range, the sales behind it, and how much weight each sale carries. It is produced from data rather than a visit — an estimate, not a RICS valuation.
Part 2 of 4
Check it yourself, free
Instant house valuation — with the working shown — no account, no email wall.
Part 3 of 4