How do you calculate the area of baseball field?

Inside the bases is easy, this is a square A=l*w say 90 feet times 90 feet = 8100 sq feet. From home plate to out field fence, this is 1/4 of circle (approx) area of circle is pi * radius squared. distance from plate to outfield fence is radius. So 340 feet for example squared, times 3.14 divded by 4 would equal 90,746 square feet. To get area of region beyond the bases, just subtract the figures.