To determine the acreage from a perimeter, the perimeter measurements must offer sufficient information to deduce the area of the enclosed shape. The formula and necessary information differs depending on the shape. Acreage can be determined from any unit of length or area, although different conversion formulas are needed for metric units and imperial units of measurement.

**Determine the area's width, length and radius**Using the perimeter information, determine the length and width of the selected area. For circular enclosures, divide the circumference by the product of two times pi to derive the radius.

**Calculate square footage**Calculate the total area of the shape. For rectangular areas, calculate the area by multiplying the length of the width by the length of the height. For triangular areas, multiply the width by the height and then divide the product in half. For circles, multiply the square of the radius by pi to calculate the area. The resulting area can be expressed as the square of the units used for the perimeter.

**Convert to acres**For an area expressed in square feet, divide the unit by 43,560 to determine the acreage. For square meters, divide the area by 4,046.85 to convert to acres.