Acreage calculator

The three paths are honest about themselves. A rectangle is exact. Four sides need one extra measurement to be exact: a diagonal splits the plot into two triangles, or two corner angles pin the shape, and without either the sides are assumed to sit on a circle, which usually reads a little high or low. GPS corners are integrated on a sphere of mean Earth radius, good to a few percent for ordinary plots, not survey-grade. Walk the corners in order around the plot, clockwise or counterclockwise; a zigzag order folds the shape over itself and understates the area. The regional units carry their own caveat: bigha changes by district, so it takes your local square-foot value, while guntha (1,089 sq ft), cent (435.6 sq ft), and kanal (5,445 sq ft) are fixed definitions.