How much acreage is 12150 sq ft?
12,150 sq ft =0.295 acre
one acre =43 560 square foot
To convert sq ft to acres divide sqft by 43,560. To convert acre to sqft multiply acre by 43,560. This is for traditional measurements, ther are rather arcane measurements Surveyors acre and sqft and suburban acre and sqft. Don't worry about it too much.
Onlineconversion .com can convert all sorts of stuff. Under area they got hectares, homestead, stangs, townships, converta township to sq mm if you want.