How we calculate land value

The central idea is simple: the value of a property is the value of its land plus the value of the building on it. If we can estimate what the building is worth, whatever is left over is the land value.

Land value = sale price − rebuild cost of the building

1. Sale price

We start from HM Land Registry Price Paid data: the recorded price of actual residential transactions across England and Wales. This is the only figure in the chain that is observed directly rather than estimated.

2. Rebuild cost (the building)

We estimate what it would cost to rebuild the structure from scratch:

• Floor area and age band come from the property's Energy Performance Certificate (EPC).
• A build-cost table gives a cost per m² by age band and property type.
• A regional multiplier adjusts for local construction costs.

Rebuild cost = floor area × cost per m² × regional multiplier.

The build-cost figures are indicative estimates on a reinstatement (insurance-rebuild) basis — what it would cost to rebuild the structure including demolition, professional fees and VAT. They are calibrated against public UK rebuild-cost data, including the ABI / BCIS house-rebuilding cost guidance (the basis insurers use for buildings sums-insured) and published UK construction-cost tables. They are broad averages for standard-specification construction: they don’t capture luxury or budget finishes, extensions, or non-standard and listed buildings, and the regional spread is deliberately conservative. They’re calibrated to that public data rather than read directly from it, so treat them as a reasoned estimate of the building’s worth, not a surveyor’s valuation.

3. Land value

Subtract the rebuild cost from the sale price and you have an estimate of the land value for that property. Aggregated across a district and time-weighted toward recent sales, this gives the median land value shown on the map.

4. Land-value density

Where we can locate a property on a land parcel (a freehold plot boundary from INSPIRE, or a building footprint as a fallback) we divide its land value by the area of that parcel to get land-value density (£ per m² of land). For flats, the shared plot is apportioned between dwellings by floor area. Density is the metric closest to what a land value tax would actually assess.

Confidence and honesty about the gaps

Not every sale matches cleanly to an EPC or a plot. We grade each property's confidence (exact match, imputed, or excluded) and only include higher-confidence sales in the headline medians. In the explorer, every figure is clickable: you can see the exact inputs, the source of each one, and whether a sale was included or not.

Sources

• HM Land Registry Price Paid Data — sale prices, property type, tenure (Contains HM Land Registry data © Crown copyright)
• Energy Performance Certificate Open Data — floor area, construction age band, built form
• HM Land Registry INSPIRE Index Polygons (freehold land parcels) and OS Open Map Local building footprints — land area
• ONS Open Geography Portal — LSOA, district and regional boundaries (Source: ONS, licensed under the Open Government Licence)
• ONS Census 2021 — tenure context
• Rebuild-cost model calibrated against ABI / BCIS rebuilding-cost guidance, the BCIS House Rebuilding Cost Index and published UK construction-cost tables

Ready to see it in action? Open the interactive map →