Dit Link bestaat niet in uw taal, Bekijk in: English (en),
Of gebruik Google Translate:  

http://edn.link/amazongpsarea

This link takes one to Amazon to view a list of GPS-based area measurement devices.  We have no particular recommendation.  This is a starting point for the concept of area measurement.  Note that there are some that have more capability for international use - units of measure, language, etc.