You can use the geocoding api from Google.
https://developers.google.com/maps/documentation/geocoding/intro#GeocodingResponses
The geometry section should help you
"geometry" : {
"location" : {
"lat" : 37.4224764,
"lng" : -122.0842499
},
"location_type" : "ROOFTOP",
"viewport" : {
"northeast" : {
"lat" : 37.4238253802915,
"lng" : -122.0829009197085
},
"southwest" : {
"lat" : 37.4211274197085,
"lng" : -122.0855988802915
}
}
},
You can calcute the area from the difference between the northeast and southwest long/lat in viewport