Korean vs Japanese Area Units
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| Aspect | Korean Area Units (평, 돈) | Japanese Area Units (坪, 畳, 間) |
|---|---|---|
| Primary unit | Pyeong (평) = 3.3058 m² | Tsubo (坪) = 3.3058 m² |
| Sub-unit for floor area | No standard sub-unit in modern use | Tatami (畳) ≈ 1.653 m² (half-tsubo, varies by region) |
| Regional variation | Pyeong is uniform nationwide | Tatami size varies: Kyoto > Tokyo > Nagoya |
| Apartment listings | Pyeong dominant in informal speech | m² dominant; tsubo declining |
| Land transactions | Pyeong used; m² on official documents | Tsubo still common for rural land |
| Legal status | Non-SI; m² required on official docs | Non-SI; supplementary use permitted |
Korea and Japan share the pyeong/tsubo unit (both equal 400/121 m², or ≈3.3058 m²) but diverge sharply once you move to sub-units. Korea has effectively abandoned traditional sub-divisions of pyeong for modern real estate; Japan retains a rich ecosystem of area units rooted in the traditional shaku-kan measurement system.
The Conversion Formulas
For both pyeong and tsubo:
And for the Japanese tatami mat:
The tatami formula uses a regional coefficient because tatami mats are not a fixed size. Use Pyeong Converter for Korean conversions and Tsubo Converter for Japanese conversions including regional tatami variants.
Japan's Regional Tatami Variation
This is where Japanese area measurement becomes genuinely complicated. One tsubo equals two tatami mats — but the physical size of a tatami mat differs by region:
| Region | Tatami size | m² |
|---|---|---|
| Kyoto (Kyoma) | 191 × 95.5 cm | 1.824 |
| Tokyo (Edoma) | 176 × 88 cm | 1.549 |
| Nagoya (Chukyo) | 182 × 91 cm | 1.656 |
A 6-tatami room in Kyoto is meaningfully larger than a 6-tatami room in Tokyo. Foreign buyers, architects, and interior designers must confirm which tatami standard applies to any given listing.
Korea's Simplified System
Korean pyeong usage is comparatively uniform. A pyeong is a pyeong across Busan, Seoul, and Jeju. The only confusion arises between exclusive area (전용면적, the interior usable space) and supply area (공급면적, which includes common areas allocated to the unit). Korean apartment listings often quote supply area in pyeong, which will be larger than the actual living space.
Practical Takeaway for International Comparison
When comparing Korean and Japanese property sizes, the headline pyeong/tsubo number is directly comparable (same unit). The hidden complexity lies in Japanese sub-units: a Japanese listing quoting "8 tatami" could represent anywhere from 12.4 m² (Tokyo) to 14.6 m² (Kyoto). Always convert to m² for unambiguous international comparisons.
Verdict
Pyeong (Korea) and tsubo (Japan) are the same base unit and directly comparable. Japanese area measurement is more complex due to regional tatami size variation; always convert to m² when comparing Japanese and Korean property sizes to avoid regional ambiguity.