It can be hard to calculate manually the mix-up of meters/acres/miles/hectars etc...
You can use this online calculator to solve any cost-for-area calculation, where units for cost and for given area are different.

Examples:

• calculate price of land, if you know the price (ex. 100 USD for one acr) and size of area (ex. 205 square meters)
• find the price of one meter of your flat - if you know the total price and its size
• check how much paint you need to have 100 square meters of a wall painted and you know the paint expenditure per meter
• find how much glue is needed, to cover the wall with the wall-paper or wall-tiles
• know how much a quantity of seed you need to plant your own lawn in front of your house

Notice that "the cost for a piece of area" has the same meaning as "meterial expenditure for a piece of area" - there is just no difference if you count the costs in US Dollars, or in tons, pounds, kilograms, litres or gallons.

This calculator can really help a lot, when you are buying a flat, purchasing some ground, building your own home... Now you can compute some price-to-area relations really fast !

• improvenet.com: more area based calculators (carpet, ceramic, painting etc. cost)
  
• calculator.net: roofing area calculator
  
• nationwide.co.uk: house price calculator