Here is a list of common area units used in different systems of measurement:

1. Metric (SI) Units:

• Square Meter (m²) – The base unit of area in the metric system. It is the area of a square with sides of 1 meter.
  
  

• Square Kilometer (km²) – A larger unit of area, commonly used to measure large areas such as countries or regions.
  
  

• Hectare (ha) – Commonly used in land measurement, especially in agriculture. 1 hectare = 10,000 square meters.
  
  

• Are (a) – A unit used in land measurement, where 1 are = 100 square meters.
  
  

2. Imperial Units:

• Square Foot (ft²) – A unit of area commonly used in the US and UK, equal to the area of a square with sides of 1 foot.
  
  

• Square Yard (yd²) – A unit of area used in the Imperial system, where 1 square yard = 9 square feet.
  
  

• Acre (ac) – A unit of area used in land measurement, particularly in the United States. 1 acre = 43,560 square feet.
  
  

• Square Mile (mi²) – A unit of area commonly used for large areas like cities, states, and countries. 1 square mile = 640 acres.
  
  

3. US Customary Units:

• Square Inch (in²) – A unit of area commonly used in the US, equal to the area of a square with sides of 1 inch.
  
  

• Square Foot (ft²) – Used the same way as in the Imperial system, where 1 square foot = 144 square inches.
  
  

• Square Yard (yd²) – Same as in the Imperial system, where 1 square yard = 9 square feet.
  
  

4. Other Area Units:

• Barn (b) – A very small unit of area used in nuclear physics to describe cross-sections of atomic nuclei. 1 barn = 10⁻²⁸ square meters.
  
  

• Moo (moo) – A unit used in South Africa for land area. 1 moo = 1,000 square meters.
  
  

• Ping (坪) – A traditional Chinese unit of area used for measuring indoor space, especially in Taiwan. 1 ping = 3.306 square meters.
  
  

• Rood – A unit of area used in agriculture. 1 rood = 1/4 of an acre = 10,890 square feet.
  
  

5. Area Units in Astronomy (Large Areas):

• Hectoparsec (hpc) – A unit used in astronomy to measure large areas, particularly in the study of galaxies. 1 hectoparsec = 10² square parsecs.
  
  

• Square Astronomical Unit (au²) – Used in astronomy to describe areas on the scale of the Solar System. 1 au² = (1 AU)², where AU is the average distance between the Earth and the Sun.
  
  

Area Conversion Formulas Between Units:

Here are the key conversion relationships between various area units:

1. Square Meters to Other Units:
   
   

   • 1 m² = 10.764 ft² (Square Feet)
     
     

   • 1 m² = 0.0002471 ac (Acres)
     
     

   • 1 m² = 0.0001 ha (Hectares)
     
     

   • 1 m² = 0.0000001 km² (Square Kilometers)
     
     

   • 1 m² = 100 b (Barns)
     
     

2. Square Feet to Other Units:
   
   

   • 1 ft² = 0.092903 m²
     
     

   • 1 ft² = 144 in² (Square Inches)
     
     

   • 1 ft² = 0.000022957 ac (Acres)
     
     

   • 1 ft² = 0.0000092903 km² (Square Kilometers)
     
     

3. Acres to Other Units:
   
   

   • 1 acre = 43,560 ft²
     
     

   • 1 acre = 4,840 yd² (Square Yards)
     
     

   • 1 acre = 4046.86 m²
     
     

   • 1 acre = 0.00404686 km² (Square Kilometers)
     
     

   • 1 acre = 10 roods
     
     

4. Square Yards to Other Units:
   
   

   • 1 yd² = 0.836127 m²
     
     

   • 1 yd² = 9 ft²
     
     

   • 1 yd² = 0.00008361 ac (Acres)
     
     

5. Square Miles to Other Units:
   
   

   • 1 mi² = 2,589,988.11 m²
     
     

   • 1 mi² = 640 acres
     
     

   • 1 mi² = 3,097,600 yd²