Pyeong to square meters
One pyeong is 3.3058 square meters. Not a rounded figure — it comes out of the fraction 400/121.
Converter
1 pyeong = 400/121 m² = 3.305785… m² · 1 m² = 0.3025 pyeong · 1 pyeong = 35.583 sq ft
Where 3.3058 comes from
A pyeong is a square. One kan on each side.
One kan is six cheok. And the cheok was fixed at 10/33 of a meter by Japan's 1891 weights and measures law — a fraction invented to force an old carpenter's unit onto the metric system.
So each side is 6 × 10/33 = 20/11 meters, about 1.818 m. Square it.
(20/11)² = 400/121 = 3.3057851…
3.3058 is that rounded. 3.3 is a cruder cut. On a small apartment nobody notices. On land it shows: 1,000 pyeong at 3.3 gives 3,300 m², the true figure is 3,305.8 m². Almost six square meters disappear.
It is not a Korean unit
The Japanese tsubo (坪) is the same size. So is the Taiwanese ping. All three are 3.3058 m².
They match because they come from the same definition. Japan fixed the cheok at 10/33 m in 1891, and that definition went into the cadastral surveys of colonial Korea and Taiwan. The unit outlived the administration that imposed it.
A Seoul apartment listing in 2026 is quoting a number that was settled in Tokyo in 1891.
Banned in 2007. Still in use.
Since 1 July 2007 it has been illegal in Korea to use pyeong in transactions and official documents. Area must be in square meters. Weight must be in grams and kilograms — which also killed the don for gold and the geun for meat, on paper.
Enforcement is a fine. A warning, then a second warning, then 500,000 won.
And yet every agent in Seoul will tell you the apartment is 34 pyeong.
The law reached the paperwork, not the language. The contract says 112.37 m². The conversation says 34 pyeong. That split has held for almost twenty years.
A unit does not die because a statute kills it. It dies when people stop remembering prices in it. Pyeong survives because Koreans store apartment prices as won per pyeong, and no law can reach that.
This is where foreign buyers lose money
The 34 in "34 pyeong" is gross floor area. It is not the space you live in.
| Korean term | What it includes | Typical |
|---|---|---|
| 전용면적 — net | Inside your front door | 84 m² (25.4 py) |
| 공급면적 — gross | Net + stairs, corridor, elevator | 112 m² (33.9 py) |
| 계약면적 — contract | Gross + parking, management office | varies |
Korea's most common apartment is 84 m² net. That is 25.4 pyeong. It is advertised as 34 pyeong. Same apartment.
The ratio is around 75%. 84 ÷ 112 = 0.75. A quarter of what you pay for is hallway and elevator shaft.
What the error costs
Take an apartment of 112 m² gross at 1 billion won. Work out the price per pyeong.
| Basis | Area | Won per pyeong |
|---|---|---|
| Gross (as advertised) | 33.9 py | 29,510,000 |
| Net (what you occupy) | 25.4 py | 39,350,000 |
Same apartment. Same billion won. The two figures are 33% apart.
North American and most European listings quote usable area. Corridors are not in the price. Bring that habit to a Korean listing and Seoul looks cheaper than it is — by roughly a third.
To compare honestly, convert the Korean property to net area first, then divide.
Conversion table
| Pyeong | m² | sq ft | Commonly called |
|---|---|---|---|
| 1 | 3.31 | 35.6 | — |
| 10 | 33.06 | 355.8 | — |
| 18 | 59.50 | 640.5 | 59 m² small unit |
| 25.4 | 84.00 | 904.2 | 84 m² net — the standard |
| 33.9 | 112.00 | 1,205.6 | "34 pyeong" |
| 45 | 148.76 | 1,601.2 | — |
| 100 | 330.58 | 3,558.3 | — |
| 1,000 | 3,305.79 | 35,583 | — |
For land: 1 hectare = 10,000 m² = 3,025 pyeong. 1 acre = 4,046.86 m² = 1,224 pyeong.
★ Questions people actually ask
- Is a pyeong 3.3 m² or 3.3058 m²?
- 3.3058 m², exactly 400/121. The 3.3 figure is for mental arithmetic. Past a few hundred pyeong the gap becomes real area.
- Is "34 pyeong" the same as 84 m²?
- Usually yes — the same apartment. 34 pyeong is gross area, 84 m² is net area. Net 84 m² converts to 25.4 pyeong.
- If the unit is banned, why is it in every listing?
- The ban covers written transactions and advertising. Spoken use is not penalised, and the spoken habit never changed.
- Is the Japanese tsubo the same as a pyeong?
- Identical. 3.3058 m². Both descend from the same 1891 definition of the cheok/shaku.
- Should I compare Korean prices per pyeong using gross or net area?
- Korean market convention is gross. If you are comparing against property outside Korea, recalculate on net area first. The two differ by more than 30%.