Section of Land Size: 640 Acres & Quarter Sections

A standard section in the U.S. Public Land Survey System is nominally one square mile, or 640 acres. Its idealized square dimensions are one mile by one mile, equivalent to 5,280 × 5,280 feet.

A quarter section is one-fourth of that standard area: 160 acres. In the ideal square arrangement, it measures half a mile by half a mile, or 2,640 × 2,640 feet.

The USDA Forest Service describes a section as nominally one mile square. “Nominally” matters: the standard grid is a size reference, not proof of the acreage or boundaries of an actual parcel.

In feet, the standard section is 5,280 × 5,280. A square quarter section is 2,640 × 2,640, and a square quarter-quarter section is 1,320 × 1,320.

The BLM's land-description explanation illustrates the subdivision of a normal 640-acre section. These reference dimensions assume that regular arrangement.

A half section can be represented as a rectangle one mile by half a mile. Its area is 320 acres even though it is not square.

Divide the ideal one-mile square into four equal squares:

                       1 mile total
               +-------------+-------------+
               |     NW      |     NE      |
               |  160 acres  |  160 acres  |
    1 mile     +-------------+-------------+
    total      |     SW      |     SE      |
               |  160 acres  |  160 acres  |
               +-------------+-------------+
                     Total: 640 acres

Conceptual grid, not a scale map or property-boundary survey.

NW, NE, SW and SE identify northwest, northeast, southwest and southeast quarters in the illustrated arrangement. Each ideal quarter is half a mile wide and half a mile tall.

For a visual reference to the side length, see one mile visualized. The one-mile line measures length; the entire square encloses one square mile of area.

A quarter section and a quarter acre are very different areas:

A standard quarter section contains 640 times the area of a quarter acre: 160 ÷ 0.25 = 640. See the quarter-acre size guide for that much smaller reference.

The word “quarter” needs the thing being divided. A quarter of a 640-acre section is 160 acres; a quarter of one acre is only 0.25 acre.

A square with quarter-mile sides is another distinct description. Its area is 40 acres, corresponding to the ideal quarter-quarter section above—not a 160-acre quarter section.

The National Wildfire Coordinating Group's land-navigation training explains that sections can be larger or smaller than standard dimensions where survey errors or corrections have occurred.

Use the standard 640-acre and 160-acre figures to understand the terminology and arithmetic. They do not replace the records and survey information for a specific location.

Likewise, a diagram showing four equal quarters should not be used to locate a real boundary on the ground. Actual recorded dimensions and the relevant survey information are needed.

This guide explains size relationships. It does not determine ownership, access or a particular parcel's boundaries.

How many acres are in a ¼ section?

A quarter of a standard 640-acre section is 160 acres: 640 ÷ 4 = 160.

What are the dimensions of a section in feet?

The ideal one-mile-square reference is 5,280 × 5,280 feet. Actual surveyed dimensions may differ.

What are the dimensions of a quarter section?

In the ideal square grid, 2,640 × 2,640 feet, or half a mile on each side.

Is every 160-acre property a square quarter section?

No. An area figure alone does not establish shape or its description within a survey system.

Does “a quarter of land” always mean 160 acres?

The phrase can be ambiguous. When it refers to a standard quarter section, the reference is 160 acres. Check the full description rather than assuming it means a quarter acre.