Introduction
Many Chinese investors who purchase real estate in Japan often notice a puzzling detail: the “registered area” recorded in the property registry (公簿面積 / kōbo menseki) does not always match the “actual measured area” (jissoku menseki) determined by a professional survey.
How can the same piece of land or the same building have two different numbers?
In fact, this is neither an error nor a sign of misinformation—it arises from Japan’s unique real estate registration system, its historical surveying methods, and the legal framework that governs property rights.
This article explains, from an investor’s perspective, the difference between registered and measured areas, the reasons behind the discrepancy, and what foreign buyers should pay attention to in property transactions.
1. Why Does Japan Have Both “Registered Area” and “Measured Area”?
In Japan, land is generally represented by two different area figures: the registered area and the measured area.
The registered area refers to the size recorded in the official property registry (Real Estate Registry) maintained by the Legal Affairs Bureau. This is a government record that appears on official documents such as the Registration Certificate of Property Information. However, the registered figure does not necessarily reflect the exact, real-world dimensions of the land.
One reason is historical. Many of Japan’s land area records date back to the Meiji era (late 19th century), when surveying techniques were rudimentary. Land was often measured by rope or visual estimation, and property boundaries were not always precisely determined. These old records were inherited without revision, meaning that many registered areas no longer match current physical conditions.
Furthermore, the registered area serves primarily administrative and tax purposes—it is used to calculate property tax, city planning tax, and inheritance tax. It is not directly linked to the property’s market price.
By contrast, the measured area is determined by a certified land surveyor using modern technology such as GPS or laser measurement tools. It represents the land’s actual, physical condition, and is critical for development, boundary verification, and sales.
The difference between these two numbers may result from outdated data, unclear boundary lines with neighboring plots, changes in terrain such as landfills or erosion, or even small conversion errors between traditional Japanese units (tsubo) and square meters.
Japan’s property registration system is designed primarily to protect ownership, not to guarantee measurement accuracy. For this reason, real estate transactions in Japan are often concluded based on the “measured sale” (jissoku uribai) principle—meaning that the transaction price is determined according to the actual measured area. If the measured area differs from the registered one, the buyer and seller adjust the price through a difference settlement to ensure fairness.
In short, the registered area serves as a legal and administrative reference point, while the measured area reflects the property’s real market condition. This dual framework is a defining characteristic of Japan’s real estate system, balancing legal clarity with practical accuracy.
2. Do Buildings, Such as Condominiums or Houses, Also Have “Registered” and “Measured” Areas?
Yes—but unlike land, the difference is usually minimal.
Because buildings have fixed structures and clearly defined physical boundaries such as walls and beams, measurement errors are rare.
The registered area (登記面積) refers to the floor area recorded in the property registry when the building is completed. This figure is based on architectural plans submitted during the building approval process.
In condominiums, it corresponds to the “exclusive-use area” of each unit. The measured area, on the other hand, refers to the space measured inside the property.
The variation mainly comes from two measurement methods used in Japan: the wall-center method (heishin menseki), which measures from the center line of walls and is used for registration, and the interior method (uchinori menseki), which measures only the usable interior space. Because the registered area is based on the wall-center method, it is usually slightly larger than the space an owner can actually use. This is a difference of measurement standards—not a mistake or exaggeration.
For modern constructions, especially new condominiums and recently built houses, high-precision measurement and CAD-based design at the building confirmation stage ensure that the registered and actual areas almost always match. Only older or repeatedly renovated properties tend to show noticeable discrepancies.
Importantly, Japan’s real estate pricing is not determined solely by the simple formula “price = area × unit price,” as is often the case in China. Japanese property values depend on a combination of factors—location, accessibility, building quality, brand reputation, management standards, and surrounding amenities.
Thus, a few square meters of difference rarely affect the transaction price in any meaningful way.
Moreover, Japan does not distinguish strictly between “registered area” and “measured area” for buildings. Since the area is precisely calculated and recorded during the building’s approval and registration stages, the registry figure is regarded as legally reliable. In practice, re-measurement or correction is rarely necessary.
3. If the Registered Area of a Building Differs from the Measured Area, Should It Be Corrected?
Some investors may wonder whether correcting a discrepancy between the registered area and the actual measured area would increase the property’s value.
In Japan, the answer is generally no.
The building’s area has already been precisely calculated at the time of construction approval, and the number recorded in the property registry is the legally recognized standard. Because building boundaries are physically fixed and clearly defined, small discrepancies do not affect ownership rights or market value.
Even if an investor hires a surveyor to remeasure and finds a slight difference, amending the registration would involve extra cost and administrative work—with virtually no benefit to property value.
In condominiums, where each unit’s area is legally tied to shared ownership proportions of common spaces, it is practically impossible to modify the area of a single unit.
Therefore, within Japan’s real estate market, the registered area is treated as the standard for transactions, while the measured area is mainly relevant for land deals.
For investors, what truly matters is not a minor numerical deviation, but the property’s profitability, location, construction quality, and legal stability.
The key to successful investment lies in evaluating sustainable asset value, not in fine-tuning registration data.
4. Conclusion
In Japanese land transactions, discrepancies between registered and measured areas are relatively common. This is why land sales often include on-site surveys and area-based price adjustments to prevent disputes.
However, for buildings—especially condominiums—such differences are negligible. Thanks to Japan’s strict building verification and registration systems, the registered area can be regarded as the accurate and official measurement.
To summarize: when purchasing land, it is wise to confirm the measured area with a professional surveyor; when buying buildings, using the registered area as the standard is perfectly sufficient.
Japan’s real estate market is renowned for its transparency, data precision, and legal reliability—qualities that continue to attract high-net-worth investors from China and around the world.