What Is an Acre?

In the U.S. customary system, an acre is defined as 43,560 square feet. While the shape can vary—180 ft × 242 ft, 90 ft × 484 ft, or 10 ft × 4,356 ft—all these configurations equal one acre.

Why Use Acres?

Acres provide a convenient, flat‑surface measurement for land, ideal for lots, farms, and public areas. For example, Denali National Park covers more than 6 million acres—an area equivalent to 261 billion square feet.

Because acres represent a level, two‑dimensional area, they ignore elevation changes, simplifying calculations compared to square feet or square miles.

Converting Acres to Square Feet

Multiply the number of acres by 43,560.

• Example 1: 0.1 acre × 43,560 sq ft / acre = 4,356 sq ft.
• Example 2: 0.5 acre × 43,560 sq ft / acre = 21,780 sq ft.

Converting Square Feet to Acres

Divide the square footage by 43,560.

• Example: 10,890 sq ft ÷ 43,560 sq ft / acre = 0.25 acre.

These simple formulas enable quick, accurate conversions for real‑estate, agriculture, and land‑planning professionals.