Core answer: 1 mu (亩) = 666.67 m²; 1 hectare = 15 mu = 10,000 m²; 1 acre = 4,047 m² ≈ 6.07 mu; 1 km² = 100 hectares = 1,500 mu. A standard football pitch is 7,140 m² ≈ 10.7 mu — the universal mental anchor for "how big is that land".
The conversion tables
| Unit | Equals | Metric |
|---|---|---|
| 1 平方丈 | 100 平方尺 | 11.11 m² |
| 1 亩 | 60 平方丈 | 666.67 m² |
| 1 顷 | 100 亩 | 6.67 hectares |
| 1 公顷 | 15 亩 | 10,000 m² |
| Unit | Metric | Note |
|---|---|---|
| 1 acre | 4,047 m² | US/UK land |
| 1 hectare | 2.471 acres | metric land |
| 1 km² | 247.1 acres | 100 ha |
| 1 sq ft | 0.0929 m² | HK apartments |
| 1 ping (坪) | 3.306 m² | Taiwan/Japan property |
Worked examples
Example 1 — Farmland. A family farms 8 亩: 8 × 666.67 = 5,333 m² ≈ 0.53 hectare ≈ 0.75 football pitches.
Example 2 — Hong Kong flat. "500 sq ft" = 500 × 0.0929 = 46.5 m² — roughly a compact two-bedroom on the mainland.
Example 3 — Taiwan apartment. 30 坪 = 30 × 3.306 = 99.2 m²; but check if 公摊 (shared area) is included — Taiwanese 坪 usually includes it.
Example 4 — US ranch listing. "40 acres" = 161,874 m² = 16.2 ha = 243 亩 ≈ 22.7 football pitches.
Why area conversions square the length factor
1 m = 3.281 ft, so 1 m² = 3.281² = 10.76 sq ft — the factor SQUARES. The classic error: converting 100 m² as 328 sq ft instead of 1,076. Same logic: 1 m² = 10,000 cm², not 100.
Common mistakes and myths
- Linear-thinking area — forgetting to square the length conversion (1 m² ≠ 3.28 sq ft).
- Acre vs hectare — a hectare is ~2.5 acres; mixing them misprices land by 150%.
- ㎡ vs 建筑 vs 套内 — Chinese property quotes gross area (建筑面积, includes shared corridors); usable area (套内) is typically 75–85% of it.
- Assuming 亩 is obsolete — farmland, tea plantations, and policy documents still quote 亩; the hectare-mu pair (15:1) is essential in rural contexts.
- Forgetting big-picture sanity checks — a "2,000 m² villa" claim is 3 亩 of floor area — implausible for a house, likely the plot.