Exam math
Area, acreage and section conversion
Start with three land-measurement constants: 43,560 square feet in an acre, 640 acres in a standard section, and 36 sections in a standard survey township. Use them to convert a rectangular parcel or solve a fractional section description.
Your figures
Used to value the parcel. Land is often quoted per acre and sometimes per square foot, so check which the question gives you.
Parcel size
1 ac
43,560 square feet. Divide square feet by 43,560 to convert to acres.
This model uses a standard 640-acre section
The three constants
One acre is 43,560 square feet. One standard section is one square mile, which is 640 acres. A standard survey township is 36 sections, six miles by six miles. Use the dimensions and fractions stated in the question; actual surveyed parcels can differ from these standard measurements.
Complete results, no email, no account. Calculation methods are checked with regression cases. Inspect your inputs, units and the stated assumptions. How we verify
Fractional section descriptions
Read a description such as the NW 1/4 of the SE 1/4 from the end backwards, dividing as you go. Or multiply the denominators and divide 640 by the result, which is faster.
40 acres
640 ÷ (4 × 4) = 640 ÷ 16 = 40
Value at $300,000 an acre: $12,000,000
How this is calculated
Rectangular parcels are width times depth for square feet, divided by 43,560 for acres, or divided by nine for square yards. An irregular lot is normally split into rectangles and triangles and summed, with a triangle being half the base times the height.
The rectangular survey system runs on townships and sections. A standard township is six miles by six miles, containing 36 sections. A standard section is one square mile, or 640 acres. Survey corrections and irregular boundaries can produce different acreages. Section 1 sits in the north-east corner and numbering runs right to left, then left to right on the next row, ending at section 36 in the south-east corner.
To read a fractional description, work from the end backwards and divide, or multiply the denominators together and divide 640 by the product. The NW 1/4 of the SE 1/4 is 640 divided by 16, which is 40 acres. Chaining more divisions works the same way: quarter of a quarter of a quarter is 640 divided by 64, which is 10 acres.
The other two description methods, metes and bounds and lot-block-tract, are covered in Property Ownership and Land Use Controls.
Common questions
How many square feet are in an acre?
43,560 square feet. A lot 220 feet by 198 feet is exactly one acre, which is a useful check figure to carry into the exam.
How many acres are in a section?
A standard section contains 640 acres, or one square mile. A standard six-by-six-mile township has 36 sections. Actual surveyed acreage can differ, so use a supplied acreage when the problem gives one.
How do you calculate the acreage of a fractional section description?
Multiply the denominators of every fraction in the description and divide 640 by the product. The NW 1/4 of the SE 1/4 gives 4 times 4, which is 16, and 640 divided by 16 is 40 acres. Reading the description right to left and dividing step by step gives the same answer.