The arithmetic is easy; the definition is not
Price divided by area looks objective, but “area” may describe a different legal or physical measure. State the yen price, exact square metres, definition, source document and whether parking, land or tax is included. If the denominator is unknown, do not publish the rate.
This matters most when small measurement differences are multiplied across expensive urban property or when marketing and registry records are compared.
Condominium area can use two systems
Condominium marketing commonly refers to wall-centre area, while registered exclusive area is generally measured differently and can be smaller. Balcony area is usually listed separately and is not the same as owned internal floor. Storage, roof terrace or parking may have distinct rights.
Compare units using the same stated basis. If one observation has only registered area and another only marketing area, retain both raw facts and avoid a false precise adjustment unless plans support it.
Houses have land and building denominators
A house transaction combines land and building. Price per land square metre ignores building value and demolition or repair; price per building square metre ignores land. Separate allocation requires evidence and may differ for valuation, tax and investment analysis.
Building area can mean registered floor, confirmation documents or total floor area, with discrepancies from extensions or excluded spaces. Reconcile registry, approvals, plans and site observation before calculating.
Investment buildings add rentable area
Gross floor area, exclusive unit area, rentable area and net lettable area answer different questions. Rent per square metre should use the area stated in the lease or measured schedule, while acquisition price per square metre may use land or building measures. Keep these ratios separate.
Common corridors, plant and parking cost money but may not earn rent. An efficient building can produce more rentable area from the same gross floor, yet legal compliance and occupant amenity must still be verified.
Land area needs rights and usability
Registered parcel area may differ from survey, and effective usable land can be reduced by setback, slope, private-road contribution, easement or irregular shape. Leasehold and co-owned access rights cannot be compared with full freehold as if the square metres were identical.
For development, usable floor depends on road, zoning, coverage, floor-area ratio, height, shadow, fire controls and design. Land price per square metre is only a starting descriptor.
Regional averages hide property mix
MLIT and REINS statistics may report average completed price per square metre for a defined segment. The average changes when geography, age, size or quality of transacted properties changes. It is not a same-property index and must not be applied directly to a subject.
Always carry geography, period, completed versus asking status, new versus resale and area basis beside the number. A chart without these labels invites misuse.
Build a denominator audit
For the subject and each comparable, list every area from registry, contract, important-matters explanation, plan, confirmation record, lease and survey. Mark which ratio uses which area. Investigate discrepancies before averaging.
The final valuation may present several useful metrics: total price, price per consistent internal area, land residual, rent per leased area and cost per rentable area. Clarity beats one universal number.
A simple worked warning
Suppose a condominium is JPY 90 million, with 70 m² wall-centre area and 66 m² registered exclusive area. The displayed rates are about JPY 1.286 million and JPY 1.364 million per m²—a 6.1% difference with no change in price or physical unit. Comparing the first rate with a registered-area comparable would create a false discount.
Keep both ratios, label them and compare like with like. If a source publishes only one area, return to the underlying document before using the observation in an offer memo.
Primary sources
- Ministry of Justice — Real-property registration information: https://www.moj.go.jp/MINJI/minji05_00010.html
- MLIT — Real-estate information library: https://www.reinfolib.mlit.go.jp/
- East Japan REINS — Market statistics: https://www.reins.or.jp/library/trend/
Reviewed 23 August 2026. Subject plans, registry, survey and lease documents control each denominator.
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