Pyeong to Square Meters
Overview
The pyeong is the traditional Korean unit of floor area, defined as the square of six Japanese shaku and equal to exactly 400/121 square metres, or about 3.305785 m². Multiplication converts directly: a 32-pyeong apartment measures 32 × 3.3058, roughly 105.8 m². The rational fraction arises because one shaku was standardised as 10/33 of a metre, so six shaku is 60/33 = 20/11 metres and the square is 400/121 — an exact value, not a rounding. South Korea removed the pyeong from legal commercial use in 2007 and requires square metres on contracts and advertisements, yet the unit persists in everyday speech and in the conventional apartment sizes buyers recognise. A further subtlety is that listings may quote supply area including shared corridors and lobbies rather than the smaller exclusive-use area, so identical pyeong figures can describe noticeably different homes.
Variables
| Symbol | Name | Unit | Description |
|---|---|---|---|
| $pyeong$ | Area in pyeong | 평 | Traditional Korean unit of floor or land area. |
| $m²$ | Area in square metres | m² | Metric equivalent, the legally required unit in Korea. |
An Exact Rational Conversion
The pyeong is the traditional Korean unit of area, equal to the square of six shaku and therefore to exactly 400/121 square metres:
$$m^2 = pyeong \times \frac{400}{121} \approx pyeong \times 3.305785$$
A 32-pyeong apartment measures $32 \times 3.3058 \approx 105.8$ m². The conversion is a ratio of integers rather than an empirical measurement, so any decimal form is a truncation.
Sizes Koreans Recognise
Apartment stock clusters at conventional pyeong figures, and the corresponding metric areas are the ones that appear on contracts.
| Pyeong | Square metres | Typical description |
|---|---|---|
| 18 | 59.5 | Studio or one bedroom |
| 24 | 79.3 | Compact two bedroom |
| 32 | 105.8 | Standard three bedroom |
| 33 | 109.1 | The gungmin pyeongsu, the national standard size |
| 45 | 148.8 | Large three or four bedroom |
Supply Area Versus Exclusive Area
A listing quoted in pyeong may describe either the exclusive-use area of the dwelling or the supply area, which adds a share of corridors, lobbies and stairwells. Supply area typically exceeds exclusive area by twenty to thirty percent, so two homes advertised at the same pyeong figure can differ substantially in usable space. Since 2007 contracts and advertisements have been required to state square metres of exclusive area, which is why a 32-pyeong home is frequently listed as 84 m² rather than 105.8 m².
Legal Status
The Act on Measurement removed the pyeong from lawful commercial use in July 2007, with penalties for non-compliant advertising. The unit nonetheless remains the dominant idiom in conversation, in agent discussions and in interior-design pricing.
Derivation & History
Meiji-era legislation fixed one shaku at 10/33 of a metre when Japan aligned its traditional measures with the metric system, and the standard propagated to Korea during the colonial period. Six shaku form one ken, that is $6 \times 10/33 = 60/33 = 20/11$ metre. A pyeong is one square ken, so its area is $(20/11)^2 = 400/121$ square metres. The result, 3.30578512…, is exact and repeating; the widely quoted 3.3058 is a four-decimal truncation that introduces about 0.5 cm² of error per pyeong.
Worked Examples
Apartment listed at 25.7 pyeong
- Multiply by the exact factor: 25.7 × 400 ÷ 121 = 84.96
- Round for contract purposes: 84.96 m²
Result: ≈ 85 m²
Converting a metric contract back to pyeong
- Divide by the factor: 84.96 ÷ 3.305785 = 25.70
Result: 25.7 pyeong
Edge Cases & Limitations
Land versus floor area: Rural land is often quoted in the larger danbo (300 pyeong) or jeongbo (3,000 pyeong); mixing the units understates a plot by orders of magnitude.
Supply versus exclusive area: The single largest source of confusion in Korean listings. Always confirm which basis a pyeong figure describes.
Rounding in advertising: Rounding pyeong to whole numbers before converting can shift the metric figure by more than 1.5 m².
Balcony expansion: Legally enclosed balcony space is excluded from exclusive area but included in usable space, so identical registered areas can feel different.
Real-World Applications
Residential sale and lease negotiation, interior renovation quotations priced per pyeong, commercial rent quoted per pyeong per month, and agricultural land valuation all use the unit. Property tax assessment and registry documents use square metres, so conversion is required at nearly every transaction.