Square Mile to Acre Converter
Convert square miles to acres with our free online area converter.
Quick Answer
1 Square Mile = 640 acres
Formula: Square Mile × conversion factor = Acre
Use the calculator below for instant, accurate conversions.
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Square Mile to Acre Calculator
How to Use the Square Mile to Acre Calculator:
- Enter the value you want to convert in the 'From' field (Square Mile).
- The converted value in Acre will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Area category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Square Mile to Acre: Step-by-Step Guide
Converting Square Mile to Acre involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Square Mile = 640 acresExample Calculation:
Convert 10 square miles: 10 × 640 = 6400 acres
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
Need to convert to other area units?
View all Area conversions →What is a Square Mile and a Acre?
and Standards
Mathematical Definition
The square mile (symbol: mi², alternative: sq mi) is a unit of area in the Imperial and US Customary systems, defined as:
The area of a square whose sides each measure exactly one statute mile in length.
Formula: $$ 1 \text{ mi}^2 = 1 \text{ mile} \times 1 \text{ mile} $$
Fundamental Relationships
Within the Imperial/US System:
- 1 mile = 5,280 feet (ft) = 1,760 yards (yd)
- 1 mi² = (5,280 ft)² = 27,878,400 ft²
- 1 mi² = (1,760 yd)² = 3,097,600 yd²
- 1 mi² = 640 acres (fundamental definition)
The 640-Acre Relationship: This is not arbitrary. The US survey system was designed so that:
- 1 section = 1 square mile = 640 acres
- ½ section = 320 acres
- ¼ section = 160 acres (historically a "homestead" size)
- ⅛ section = 80 acres
- 1/16 section = 40 acres
Metric Conversions (Exact):
Based on the 1959 International Yard and Pound Agreement:
- 1 mile = 1.609344 kilometers (exactly)
- 1 mi² = (1.609344 km)² = 2.58998811033 6 km²
Practical Metric Conversions:
- 1 mi² ≈ 2.59 km² (rounded)
- 1 mi² = 258.999 hectares ≈ 259 ha
- 1 mi² = 2,589,988 square meters
Visual Representation
A perfect square mile:
- Each side: 5,280 feet = 1.609 km
- Perimeter: 4 miles = 21,120 feet = 6.44 km
- Diagonal: 1.414 miles = 7,470 feet = 2.28 km
How big is it?
- About 505 soccer fields (FIFA regulation)
- About 484 American football fields (including end zones)
- About 1,280 city blocks (assuming 200 ft × 200 ft blocks)
- A 10-minute walk from one side to the opposite side
The Mathematical Definition
1 Acre = 43,560 square feet
This definition comes from the traditional measurement:
- 1 chain = 66 feet (Gunter's chain)
- 1 furlong = 660 feet (10 chains)
- 1 acre = 1 chain × 1 furlong = 66 ft × 660 ft = 43,560 sq ft
In Other Units:
- Square Yards: $\frac{43,560}{9} = 4,840 \text{ sq yd}$
- Square Meters: $43,560 \times 0.09290304 = 4,046.856 \text{ m}^2$
- Hectares: $\frac{4,046.856}{10,000} = 0.4047 \text{ ha}$
Shape Doesn't Matter
An acre can be any shape as long as the total area is 43,560 sq ft.
- Square Acre: 208.71 ft × 208.71 ft
- Rectangular Acre: 66 ft × 660 ft (traditional furlong × chain)
- Circular Acre: Radius of 117.75 ft
- Irregular Acre: Any polygon with 43,560 sq ft area
The "Chain" System
The acre is part of an elegant measurement system based on Gunter's chain:
- 1 link = 7.92 inches (0.66 ft)
- 1 chain = 100 links = 66 ft
- 1 furlong = 10 chains = 660 ft = 1/8 mile
- 1 mile = 8 furlongs = 80 chains = 5,280 ft
- 1 acre = 10 square chains
This system made surveying incredibly efficient. A surveyor could measure land using a physical chain and easily calculate acreage.
Note: The Square Mile is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Acre belongs to the imperial/US customary system.
History of the Square Mile and Acre
and Evolution
The Roman Mile (Ancient Origins)
The word "mile" comes from the Latin "mille passus" (thousand paces).
Roman Definition:
- 1 pace (passus) = 2 steps = 5 Roman feet (pes)
- 1,000 paces = 5,000 Roman feet = 1 Roman mile
- 1 Roman mile ≈ 4,850 modern feet (about 1,480 meters)
Roman Land Measurement:
- Romans used the jugerum (about 2/3 acre) for agricultural land
- Centuriation: land divided into square grids for colonial settlements
- This grid system influenced later European land survey methods
Medieval England: Mile Chaos (500-1500 AD)
Multiple "Miles" Existed Simultaneously:
- Old London Mile: 5,000 feet
- Irish Mile: 6,720 feet (2.048 km)
- Scottish Mile: 5,952 feet (1.814 km)
- Various local miles: ranged from 4,800 to 7,000 feet
Why the confusion?
- Different regions had different "feet" lengths
- Local lords defined their own measurement standards
- Trade and legal disputes were common
The Statute Mile (1593)
Queen Elizabeth I's Parliament (1593):
- Standardized the statute mile at exactly 5,280 feet
- Made it the official measurement for England
- Named "statute" because it was defined by statute (law)
Why 5,280 feet?
- 1 mile = 8 furlongs (furlong = 660 feet, used in agriculture)
- 1 furlong = 10 chains (chain = 66 feet, standard surveyor's chain)
- This made conversions between agricultural measures convenient
Square Mile Standardization:
- As the statute mile was defined, the square mile naturally followed
- 1 mi² = 640 acres (this relationship was crucial for land sales)
British Empire and Colonial Land Surveys (1600s-1800s)
Square Mile in Colonial Administration:
- Used throughout British Empire for measuring:
- Colonial territories
- Land grants to settlers
- Administrative districts
- Natural resources (forests, mining claims)
Challenges:
- Early surveys often inaccurate (limited technology)
- Terrain (mountains, rivers) made perfect square miles impossible
- Native land claims conflicted with colonial grid systems
US Public Land Survey System (1785)
The Land Ordinance of 1785:
Perhaps the most important application of the square mile in history.
Problem: The newly independent United States owned vast unsurveyed western territories (Northwest Territory: modern Ohio, Indiana, Illinois, Michigan, Wisconsin, and part of Minnesota).
Solution: Congress passed the Land Ordinance of 1785, creating a systematic survey grid.
The System:
Township: 6 miles × 6 miles = 36 square miles
- Divided into 36 sections
- Each section numbered 1-36 (specific numbering pattern)
Section: 1 mile × 1 mile = 1 square mile = 640 acres
- The fundamental unit of sale
- Could be subdivided: half-section (320 ac), quarter-section (160 ac), etc.
Quarter-Section: ½ mile × ½ mile = 160 acres
- Became the standard homestead size (Homestead Act of 1862)
- Considered sufficient for a family farm
Impact:
- Surveyed over 1.5 billion acres (2.3 million square miles)
- Used in 30 US states (primarily west of the Ohio River)
- Created the rectangular field patterns visible from aircraft today
- Property descriptions still use this system: "SW¼ of Section 12, Township 3N, Range 4W"
States Using PLSS: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Florida, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Ohio, Oklahoma, Oregon, South Dakota, Utah, Washington, Wisconsin, Wyoming
States NOT Using PLSS (Original 13 colonies plus Texas, Hawaii, Kentucky, Tennessee, Vermont, West Virginia): These states used metes and bounds surveying (descriptive: "from the oak tree to the creek to the stone wall...").
International Yard Agreement (1959)
Standardization of the Yard/Foot/Mile:
- US, UK, Canada, Australia, New Zealand, South Africa agreed
- 1 yard = 0.9144 meters (exactly)
- 1 foot = 0.3048 meters (exactly)
- 1 mile = 1.609344 kilometers (exactly)
- 1 square mile = 2.589988110336 km² (exactly)
Why This Mattered:
- International scientific cooperation required consistent units
- Engineering projects crossing borders needed standards
- Eliminated minor differences between US and UK definitions
US Survey Foot Exception:
- US kept the "US survey foot" (1 ft = 1200/3937 m) for existing land records
- Difference: 2 parts per million (0.0002%)
- Matters for large-scale surveys spanning many miles
- Most states switched to international foot by 2023
Modern Era: Metrication and Persistence (1960-Present)
Global Metrication:
- 1965: UK began metrication (Ordnance Survey switched to km²)
- 1970: Canada officially metricated
- 1975: Australia completed metrication
- 1985: New Zealand fully metricated
US Resistance:
- Metric Conversion Act (1975): voluntary metrication—failed
- Square mile remains standard for US geography, census, planning
- All US atlases, maps, and official statistics use square miles
- Real estate still uses acres and square feet
Current Usage:
- United States: Exclusive standard for geographical areas
- United Kingdom: Mixed use (km² official, mi² still common)
- Canada: km² official, mi² understood by older generations
- Myanmar: Uses square mile
- Liberia: Uses square mile
International Organizations:
- UN, WHO, World Bank: use km²
- US Census Bureau: uses mi²
- CIA World Factbook: provides both mi² and km²
: From Oxen to GPS
Ancient Origins
The concept of measuring land by how much could be worked in a day is ancient and universal:
- Roman Jugerum: The area two oxen could plow in one day (~2/3 acre).
- German Morgen: "Morning's work" of plowing (~0.6-0.9 acres).
- French Arpent: Regional French unit (~0.85 acres).
- English Acre: The amount one man with one ox could plow in one day.
The problem? Soil quality varied. Rocky, hilly land took longer to plow than flat, fertile land. This led to regional variations in the "acre."
Medieval Chaos
In medieval England, there were dozens of different "acres":
- Statute Acre: 43,560 sq ft (the modern standard).
- Irish Acre: 7,840 sq yd (1.62 statute acres).
- Scottish Acre: 6,150 sq yd (1.27 statute acres).
- Cheshire Acre: 10,240 sq yd (2.11 statute acres).
- Cornish Acre: Varied by location.
Land disputes were common because nobody could agree on the size of an acre!
The Gunter Revolution (1620)
Edmund Gunter, an English clergyman and mathematician, invented the surveyor's chain in 1620. This 66-foot chain (divided into 100 links) became the standard tool for land measurement.
Why 66 feet?
- 1 chain = 4 rods (or poles) = 66 feet.
- 10 chains = 1 furlong = 660 feet = 1/8 mile.
- 80 chains = 1 mile = 5,280 feet.
This made calculations trivial:
- 1 acre = 10 square chains.
- 640 acres = 1 square mile.
The Homestead Act (1862)
In the United States, the Homestead Act of 1862 granted 160 acres of public land to settlers who would farm it for 5 years. This "quarter section" (1/4 of a square mile) became the iconic American farm size.
The Grid System:
- 1 section = 1 square mile = 640 acres.
- 1 quarter section = 160 acres (homestead).
- 1 township = 36 sections = 23,040 acres = 36 square miles.
This grid system is why much of the American Midwest has perfectly straight roads running north-south and east-west.
Modern Standardization
- 1878: Weights and Measures Act (UK) formalized the "statutory acre."
- 1959: International yard and pound agreement standardized the acre globally.
- Today: The acre is legally defined as exactly 4,046.8564224 square meters.
Common Uses and Applications: square miles vs acres
Explore the typical applications for both Square Mile (imperial/US) and Acre (imperial/US) to understand their common contexts.
Common Uses for square miles
Across Industries
1. Government and Census
US Census Bureau:
- Reports all geographic areas in square miles
- Population density: people per mi²
- Urban area definitions based on mi² thresholds
- Metropolitan Statistical Areas (MSAs) measured in mi²
Land Management:
- Bureau of Land Management (BLM): 247 million acres = 386,000 mi²
- US Forest Service: 193 million acres = 302,000 mi²
- National Park Service: 84 million acres = 131,000 mi²
2. Geography and Cartography
Map Making:
- US Geological Survey (USGS) maps use mi²
- Topographic maps scale in miles
- GIS software in US defaults to square miles
Geographic Information Systems (GIS):
- Area calculations reported in mi² for US audiences
- Spatial analysis uses mi² for US jurisdictions
3. Urban Planning and Development
City Planning:
- Zoning maps measured in mi²
- Service area calculations (fire, police, schools) in mi²
- Transit system coverage in mi²
Infrastructure:
- Road networks: lane-miles (length × lanes)
- Service territories: utilities measured in mi²
- Emergency response zones: mi² coverage areas
4. Real Estate (Large Tracts)
Rural Land Sales:
- Ranches: sometimes listed in mi² (though acres more common)
- Large timber tracts: mi²
- Mining claims: sections (1 mi² = 640 acres)
Commercial Development:
- Master-planned communities: hundreds to thousands of acres (multiple mi²)
- Industrial parks: often measured in mi²
5. Environmental Science and Conservation
Habitat Measurement:
- Wildlife refuges measured in mi²
- Conservation easements: large tracts in mi²
- Wetland restoration projects: mi²
Disaster Assessment:
- Wildfire extent: acres or mi²
- Flood zones: mi² inundated
- Hurricane damage: mi² affected
When to Use acres
1. Real Estate
The acre is the standard unit for land sales in the US, UK, Canada, and Australia.
Residential:
- Lot sizes for homes, especially in suburban and rural areas.
- Zoning regulations often specify minimum lot sizes in acres (e.g., "R-1 zoning: 1-acre minimum").
Commercial:
- Shopping centers, office parks, industrial sites.
- "10-acre commercial development site available."
Undeveloped Land:
- Timberland, hunting land, investment property.
- "40-acre wooded parcel with creek frontage."
2. Agriculture
Farmers use acres to:
- Measure field sizes: "I have 80 acres in corn this year."
- Calculate yields: "We harvested 180 bushels per acre."
- Apply inputs: "Apply 150 lbs of nitrogen per acre."
- Comply with regulations: "You must leave 10 acres fallow for conservation."
Crop Yields (US Average):
- Corn: 177 bushels/acre.
- Soybeans: 52 bushels/acre.
- Wheat: 47 bushels/acre.
- Cotton: 900 lbs/acre.
3. Forestry
Timber is sold by the acre.
- Managed Forest: "200 acres of pine plantation."
- Timber Yield: "This stand will produce 20 cords per acre."
4. Land Management & Conservation
- National Parks: Measured in acres (Yellowstone: 2.2 million acres).
- Wetlands: "Restore 500 acres of wetlands."
- Wildlife Habitat: "Preserve 1,000 acres for endangered species."
5. Sports & Recreation
- Golf Courses: 100-200 acres (18 holes).
- Ski Resorts: "1,500 acres of skiable terrain."
- Hunting Leases: "Lease 500 acres for deer hunting."
Additional Unit Information
About Square Mile (mi²)
How many acres are in one square mile?
Exactly 640 acres in one square mile. This is a fundamental relationship in the Imperial and US Customary systems.
Historical Origin:
- 1 acre = 1 furlong × 1 chain = 660 ft × 66 ft = 43,560 ft²
- 1 mile = 8 furlongs = 5,280 ft
- 1 mi² = (8 furlongs)² = 64 acres × 10 = 640 acres
Common Subdivisions:
- 1 mi² = 640 acres (full section)
- ½ mi² = 320 acres (half section)
- ¼ mi² = 160 acres (quarter section, homestead)
- ⅛ mi² = 80 acres
- 1/16 mi² = 40 acres
How many square kilometers are in one square mile?
One square mile equals approximately 2.59 square kilometers (2.58998811 km² exactly).
Conversion Formula: $$ 1 \text{ mi}^2 = 2.58998811 \text{ km}^2 $$
Quick Mental Math: Multiply mi² by 2.6
Examples:
- 100 mi² = 259 km²
- 1,000 mi² = 2,590 km²
- 10,000 mi² = 25,900 km²
What is a "section" of land in the US?
In the US Public Land Survey System (PLSS), a section is a unit of land area nominally equivalent to one square mile (640 acres).
Township Organization:
- 1 township = 36 sections arranged in a 6×6 grid
- Each section numbered 1-36 (specific pattern)
- Section 16 often reserved for schools (in original PLSS states)
Legal Land Descriptions:
- "SW¼ of Section 12, Township 3 North, Range 4 West" = 160 acres
- This system used in 30 US states
Actual vs Nominal:
- Sections are "nominally" 1 mi² due to survey errors and Earth's curvature
- Actual sections: typically 635-645 acres
- "Government lots" used to correct discrepancies
Is the square mile an SI unit?
No, the square mile is not part of the International System of Units (SI). It belongs to the British Imperial and US Customary systems.
SI/Metric Equivalents:
- Square kilometer (km²): SI standard for large areas
- Hectare (ha): Accepted for use with SI, especially agriculture
Global Usage:
- US: square miles standard
- UK: mixed (km² official, mi² common)
- Rest of world: almost exclusively km²
How do you visualize a square mile?
Walking Measure:
- 1 mile ≈ 20-minute walk at average pace
- Walking around a square mile: 4 miles = 80-minute walk
Grid Measure:
- Imagine 8 city blocks × 8 city blocks (if blocks are 660 ft)
- About 1,280 standard city blocks (if blocks are 200 ft × 200 ft)
Sports Fields:
- About 484 American football fields (with end zones)
- About 505 FIFA regulation soccer fields
- About 740 standard baseball diamonds
Urban Comparison:
- Downtown core of a medium city
- Major university campus
- Large shopping mall with parking lots
How big is Central Park in square miles?
Central Park (NYC): 1.317 mi² (3.41 km²) = 843 acres
Comparisons:
- 1.3× larger than a standard section
- About 6% of Manhattan's area
- Slightly larger than Monaco (0.78 mi²)
Other Famous Parks:
- Golden Gate Park (SF): 1.017 mi² (2.63 km²)
- Griffith Park (LA): 6.9 mi² (17.9 km²)
- Rock Creek Park (DC): 2.8 mi² (7.2 km²)
What is population density per square mile?
Population density is the number of people per unit area, commonly expressed as people per square mile in the US.
Formula: $$ \text{Density} = \frac{\text{Population}}{\text{Area (mi}^2\text{)}} $$
Example:
- San Francisco: 873,965 people ÷ 47 mi² = 18,595 people/mi²
Density Categories:
- Very high: >10,000 people/mi² (Manhattan: 74,000/mi²)
- High: 5,000-10,000 people/mi² (most urban cores)
- Moderate: 1,000-5,000 people/mi² (suburbs)
- Low: 100-1,000 people/mi² (rural-suburban)
- Very low: <100 people/mi² (rural)
How many square miles is Earth's surface?
Total Earth Surface: 196.9 million mi² (510.1 million km²)
Breakdown:
- Land area: 57.5 million mi² (148.9 million km²) — 29.2%
- Water area: 139.4 million mi² (361.1 million km²) — 70.8%
Continents (Land):
- Asia: 17.2 million mi² (44.6 million km²)
- Africa: 11.7 million mi² (30.4 million km²)
- North America: 9.5 million mi² (24.7 million km²)
- South America: 6.9 million mi² (17.8 million km²)
- Antarctica: 5.5 million mi² (14.2 million km²)
- Europe: 3.9 million mi² (10.2 million km²)
- Australia/Oceania: 3.3 million mi² (8.5 million km²)
Can square miles measure ocean areas?
Yes, square miles can measure ocean areas, though square kilometers are more common internationally.
Oceans by Area:
- Pacific Ocean: 63.8 million mi² (165.2 million km²) — largest
- Atlantic Ocean: 41.1 million mi² (106.5 million km²)
- Indian Ocean: 27.2 million mi² (70.6 million km²)
- Southern Ocean: 7.8 million mi² (20.3 million km²)
- Arctic Ocean: 5.4 million mi² (14.1 million km²) — smallest
Comparison:
- Pacific Ocean alone is larger than all land on Earth combined
What is the area of the continental United States?
Continental (Contiguous) United States: 3,119,885 mi² (8,080,464 km²)
This includes the "Lower 48" states (excludes Alaska and Hawaii).
Breakdown:
- Land area: 2,959,064 mi² (7,663,941 km²)
- Water area: 160,821 mi² (416,522 km²)
Total United States (All 50 states):
- Total area: 3,796,742 mi² (9,833,520 km²)
- Alaska adds 665,384 mi² (1,723,337 km²)
- Hawaii adds 10,931 mi² (28,311 km²)
About Acre (acre)
How big is an acre visually?
The easiest way to visualize an acre:
- Football Field: An acre is about 90.75% of an American football field (including end zones). The field is 120 yards × 53.33 yards = 57,600 sq ft. An acre is 43,560 sq ft.
- Square: A square acre is 208.71 feet on each side. That's about 70 yards × 70 yards.
- Walking: You can walk the perimeter of a square acre in about 3-4 minutes at a normal pace.
How many houses fit on an acre?
Depends on lot size and zoning:
- Urban (Small Lots): 8-12 houses (4,000-5,000 sq ft lots).
- Suburban (Standard): 4-6 houses (7,000-10,000 sq ft lots).
- Suburban (Large): 2-3 houses (15,000-20,000 sq ft lots).
- Rural (Estate): 1 house (entire acre or more).
Zoning Example:
- R-1 (Low Density): 1-2 units per acre.
- R-2 (Medium Density): 4-8 units per acre.
- R-3 (High Density): 12-20 units per acre.
How many acres is a football field?
American Football Field:
- With end zones: 120 yards × 53.33 yards = 57,600 sq ft = 1.32 acres.
- Without end zones: 100 yards × 53.33 yards = 48,000 sq ft = 1.10 acres.
Soccer Field (FIFA):
- Regulation: 100-130 yards × 50-100 yards.
- Typical: 110 yards × 70 yards = 56,700 sq ft = 1.30 acres.
How many acres is a city block?
Varies wildly by city:
- Manhattan (NYC): 2-5 acres (blocks are irregular).
- Chicago: ~3 acres (660 ft × 330 ft blocks).
- Portland: ~2 acres (200 ft × 200 ft blocks).
- Phoenix: ~4 acres (larger grid).
Rule of Thumb: Most US city blocks are 2-5 acres.
How many acres do I need for a house?
Minimum (Legal):
- Urban: 0.1 acres (4,356 sq ft) - typical city lot.
- Suburban: 0.25-0.5 acres - standard suburban lot.
- Rural: 1+ acres - zoning often requires minimum acreage.
Practical:
- Comfortable Home: 0.5-1 acre (room for yard, garden, privacy).
- Hobby Farm: 5-10 acres (horses, chickens, large garden).
- Self-Sufficiency: 10-20 acres (livestock, crops, timber).
How many acres do you need for farming?
Depends on the type of farming:
- Market Garden (Vegetables): 1-5 acres (intensive).
- Orchard: 5-20 acres.
- Cattle (Pasture): 1.5-2 acres per cow (varies by climate/grass quality).
- Grain Farming: 100-1,000+ acres (mechanized).
- Dairy Farm: 50-500 acres (depends on herd size).
USDA Definition of a Farm: Any place that produced and sold at least $1,000 of agricultural products during the year. This can be as small as 1 acre of intensive vegetables or as large as 10,000 acres of wheat.
How do you calculate acreage from dimensions?
For Rectangular Land: $$ \text{Acres} = \frac{\text{Length (ft)} \times \text{Width (ft)}}{43,560} $$
Example: A lot is 200 ft × 300 ft. $$ \frac{200 \times 300}{43,560} = \frac{60,000}{43,560} = 1.38 \text{ acres} $$
For Irregular Shapes:
- Divide the land into triangles or rectangles.
- Calculate the area of each section.
- Add them together.
- Divide by 43,560.
Modern Method: Use GPS or GIS software to trace the boundary and calculate area automatically.
Is an acre the same in all countries?
Mostly yes, but with variations:
- US/UK Acre (Statute Acre): 43,560 sq ft (standard).
- Irish Acre: 7,840 sq yd = 70,560 sq ft = 1.62 statute acres (historical, rarely used today).
- Scottish Acre: 6,150 sq yd = 55,350 sq ft = 1.27 statute acres (historical).
- Acre (International): Since 1959, the "international acre" is standardized at 4,046.8564224 m².
Today: When someone says "acre" without qualification, they mean the statute acre (43,560 sq ft).
Why is an acre 43,560 square feet?
It comes from the furlong × chain definition:
- 1 furlong = 660 feet (1/8 mile, the length of a traditional plowed furrow).
- 1 chain = 66 feet (Gunter's surveying chain).
- 1 acre = 1 furlong × 1 chain = 660 ft × 66 ft = 43,560 sq ft.
This was chosen because it made surveying easy with Gunter's chain (which was exactly 1 chain long).
How many acres is Central Park?
Central Park (New York City): 843 acres (1.317 square miles).
- Length: 2.5 miles (north-south).
- Width: 0.5 miles (east-west).
- Perimeter: ~6 miles.
For comparison:
- Golden Gate Park (San Francisco): 1,017 acres (20% larger than Central Park).
- Hyde Park (London): 350 acres.
Conversion Table: Square Mile to Acre
| Square Mile (mi²) | Acre (acre) |
|---|---|
| 0.5 | 320 |
| 1 | 640 |
| 1.5 | 960 |
| 2 | 1,280 |
| 5 | 3,200 |
| 10 | 6,400 |
| 25 | 16,000 |
| 50 | 32,000 |
| 100 | 64,000 |
| 250 | 160,000 |
| 500 | 320,000 |
| 1,000 | 640,000 |
People Also Ask
How do I convert Square Mile to Acre?
To convert Square Mile to Acre, enter the value in Square Mile in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our area converter page to convert between other units in this category.
Learn more →What is the conversion factor from Square Mile to Acre?
The conversion factor depends on the specific relationship between Square Mile and Acre. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.
Can I convert Acre back to Square Mile?
Yes! You can easily convert Acre back to Square Mile by using the swap button (⇌) in the calculator above, or by visiting our Acre to Square Mile converter page. You can also explore other area conversions on our category page.
Learn more →What are common uses for Square Mile and Acre?
Square Mile and Acre are both standard units used in area measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our area converter for more conversion options.
For more area conversion questions, visit our FAQ page or explore our conversion guides.
Helpful Conversion Guides
Learn more about unit conversion with our comprehensive guides:
All Area Conversions
Other Area Units and Conversions
Explore other area units and their conversion options:
- Square Meter (m²) • Square Mile to Square Meter
- Square Kilometer (km²) • Square Mile to Square Kilometer
- Square Centimeter (cm²) • Square Mile to Square Centimeter
- Square Millimeter (mm²) • Square Mile to Square Millimeter
- Square Inch (in²) • Square Mile to Square Inch
- Square Foot (ft²) • Square Mile to Square Foot
- Square Yard (yd²) • Square Mile to Square Yard
- Hectare (ha) • Square Mile to Hectare
Verified Against Authority Standards
All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.
National Institute of Standards and Technology — Standards for area measurements
Last verified: December 3, 2025