Convert Acres to Square Miles - Free ac ⇄ mi² Calculator

Convert between acres (ac) and square miles (mi²) with precision using standard area measurements

Acres to Square Miles Converter Tool
Enter a value to convert between acres and square miles with bidirectional conversion (1 square mile = 640 acres)
Note: This converter uses standard conversion (1 square mile = 640 acres). Perfect for large land measurements, county planning, national park areas, and extensive property calculations.

Do you need to quickly convert acres to square miles or the reverse? Our ac ⇄ mi² converter provides fast and accurate results. Whether you are measuring farmland, real estate, or geographic regions, switching between acres and square miles ensures proper land measurement.

Why Users Love This Acres ⇄ Square Miles Converter

  • Accurate formula: Uses the official US customary relationship.
  • Instant answers: Results update immediately.
  • Two-way function: Works for both acres to square miles and square miles to acres.
  • Clear output: Displays exact and rounded results.
  • Device-friendly: Works on both mobile and desktop.

How to Use the Converter

  1. Enter the value in acres or square miles.
  2. Choose the conversion direction.
  3. Get instant results.
  4. Copy, save, or share the calculation.

What is an Acre (ac)?

An acre is a unit of land area used in the imperial and US customary systems. It is smaller than a square mile but widely used in property and farming.

Key Facts About Acres

  • Exact value: 1 acre = 43,560 square feet.
  • Relationship: 640 acres = 1 square mile.
  • Abbreviation: ac.
  • Usage: Agriculture, real estate, construction, and land management.

What is a Square Mile (mi²)?

square mile is a larger unit of land measurement commonly used in geography and mapping.

Key Facts About Square Miles

  • Exact value: 1 square mile = 640 acres.
  • Relationship: 1 mi² = 2.59 square kilometers.
  • Abbreviation: mi² or sq mi.
  • Usage: Geography, state and country size, urban planning, and real estate.

Acres to Square Miles Conversion Formula

Formula:

Square Miles = Acres ÷ 640

Acres to Square Miles Conversion Example

  • 640 acres to square miles
    Step 1: Formula = mi² = ac ÷ 640
    Step 2: Substitute = 640 ÷ 640
    Step 3: Result = 1 mi²
     
  • 1280 acres to square miles
    Step 1: mi² = ac ÷ 640
    Step 2: Substitute = 1280 ÷ 640
    Step 3: Result = 2 mi²
     
  • 3200 acres to square miles
    Step 1: mi² = ac ÷ 640
    Step 2: Substitute = 3200 ÷ 640
    Step 3: Result = 5 mi²

Square Miles to Acres Conversion Formula

Formula:

Acres = Square Miles × 640

Square Miles to Acres Conversion Example

  • 1 square mile to acres
    Step 1: Formula = ac = mi² × 640
    Step 2: Substitute = 1 × 640
    Step 3: Result = 640 acres
     
  • 2.5 square miles to acres
    Step 1: ac = mi² × 640
    Step 2: Substitute = 2.5 × 640
    Step 3: Result = 1600 acres
     
  • 10 square miles to acres
    Step 1: ac = mi² × 640
    Step 2: Substitute = 10 × 640
    Step 3: Result = 6400 acres

Applications of Acres and Square Miles Conversion

  • Agriculture: Farmland is often measured in acres, while larger regions may use square miles.
  • Real Estate: Property listings may use both acres and square miles.
  • Geography: Countries and cities are mapped using square miles.
  • Construction: Large projects require accurate land area conversions.
  • Urban Planning: Towns and districts often compare space using these units.

Quick Reference Table for Acres ⇄ Square Miles

Acres (ac)

Square Miles (mi²)

Square Miles (mi²)

Acres (ac)

640 ac

1 mi²

1 mi²

640 ac

1280 ac

2 mi²

2.5 mi²

1600 ac

3200 ac

5 mi²

5 mi²

3200 ac

6400 ac

10 mi²

10 mi²

6400 ac

Use our acres ⇄ square miles converter at Digital Calculator for fast, accurate, and reliable results. Perfect for farming, real estate, construction, and geography.

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Frequently Asked Questions

Published: 9/26/2025