Reading section descriptions and finding acreage
Once you know a section is 640 acres, any regular piece of it (an aliquot part) is easy to locate and measure.
Reading the description backward
A description like this one:
The NE 1/4 of the SW 1/4 of Section 12, Township 2 South, Range 3 East, Tallahassee Meridian
is read from the end to the beginning to find the land:
- Find the township: T2S, R3E of the Tallahassee Meridian.
- Find Section 12 in that township.
- Take the SW 1/4 of Section 12.
- Within that quarter, take the NE 1/4.
Each step zooms in on a smaller square inside the one before.
Computing acreage
Multiply 640 by every fraction in the description:
| Description | Math | Acres |
|---|---|---|
| Section 12 | 640 | 640 |
| SW 1/4 of Section 12 | 640 x 1/4 | 160 |
| NE 1/4 of the SW 1/4 | 640 x 1/4 x 1/4 | 40 |
| S 1/2 of the NE 1/4 of the SW 1/4 | 640 x 1/4 x 1/4 x 1/2 | 20 |
| NW 1/4 of the NE 1/4 of the SW 1/4 | 640 x 1/4 x 1/4 x 1/4 | 10 |
A shortcut: multiply all the denominators and divide 640 by the result. For "the NE 1/4 of the SW 1/4," 4 x 4 = 16, and 640 / 16 = 40 acres. BLM treats the 40-acre quarter-quarter as its standard land unit.
The direction letters (NE, SW, N, S) tell you where the parcel is. They never change how big it is. Only the fractions matter for acreage.
"Of" versus "and"
BLM's rule: no comma (or the word "of") links pieces into one smaller parcel; a comma (or the word "and") starts a separate parcel to add.
- "NE 1/4 of the SW 1/4 of the SE 1/4" is one parcel: 640 / 64 = 10 acres.
- "NE 1/4, SW 1/4, SE 1/4" (commas) is three quarter sections: 160 x 3 = 480 acres.
- "N 1/2 of the SE 1/4 and the SW 1/4 of the SE 1/4" is two parcels: 80 + 40 = 120 acres.
When you see "and," compute each piece separately, then add.
Converting to square feet
A section is 1 mile square. A mile is 5,280 feet, so a section is 5,280 x 5,280 = 27,878,400 square feet. Divide by 43,560 square feet per acre and you get exactly 640 acres. NIST's survey tables confirm both: 1 mile = 5,280 feet, 1 acre = 43,560 square feet, 640 acres = 1 square mile.
A quarter-quarter (40 acres) is a quarter mile, or 1,320 feet, on each side.
Distances between sections
Exam questions sometimes ask how far apart two sections are. Use this method:
- Assume a standard township where every section is exactly 1 mile on each side.
- Find both sections on the numbering grid (Section 1 in the NE, numbered back and forth).
- If they are in the same row or column, count the whole sections that lie between them. Each one is 1 mile.
That count is the distance between their nearest boundaries. For example, Sections 7 and 12 are both in the second row; Sections 8, 9, 10 and 11 lie between them, so their nearest boundaries are 4 miles apart. (Measured from the far boundary of one to the far boundary of the other, add 2 miles for the two sections themselves: 6 miles, the width of the township.) Always check which measurement the question asks for.
Exam tips
- Read backward to locate; multiply forward to measure.
- 640 / (product of denominators) = acres.
- "And" means add separate parcels.