Updated May 24, 2026

Square Miles to Square Kilometers Converter

Multiply square miles by 2.59 to get square kilometers. 1 mi² = 2.59 km². For example, 100 mi² = 259 km². One square mile also equals 640 acres or 259 hectares.

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Common Conversions

Key Takeaways

  • 1 mi² = 2.58999 km². Multiply square miles by 2.59 for km².
  • 1 mi² = 640 acres = 259 hectares.
  • US states: Texas = 268,596 mi² (695,662 km²), Alaska = 665,384 mi².
  • A US land section = 1 mi² = 640 acres = 2.59 km².
  • Quick estimate: multiply mi² by 2.6 for approximate km².

How Do You Convert mi² to km²?

Multiply the number of square miles by 2.58999 to get square kilometers. The formula is: km² = mi² × 2.58999. This factor is the square of the mile-to-kilometer conversion (1.60934² = 2.58999). For quick estimates, multiply by 2.6.

Sam Okafor helps international buyers understand American property sizes. A 2,000-acre ranch near Pinewood Falls is 2,000 / 640 = 3.125 square miles, which converts to 3.125 × 2.59 = 8.09 km². His European clients immediately grasp the scale — roughly the size of a small European town.

US State Area Reference

State Area (mi²) Area (km²)
Rhode Island1,5454,001
Connecticut5,54314,357
New Jersey8,72322,591
Maryland12,40732,131
West Virginia24,23062,756
Virginia42,775110,787
Florida65,758170,312
Colorado104,094269,601
California163,696423,967
Texas268,596695,662
Alaska665,3841,723,337

Common Applications

International Communication

When sharing geographic data with international colleagues, converting from square miles to square kilometers is essential. Most countries use km² as the standard area unit. A report saying a watershed covers 450 mi² translates to 1,165 km² — the format expected by international scientific journals and UN agencies.

Wildfire and Disaster Reporting

US wildfire reports use acres and square miles, while international media uses km² and hectares. The 2020 California fire season burned about 4.2 million acres — that is 6,562 mi² or 16,997 km², an area larger than the country of Montenegro. Converting makes the scale comprehensible across audiences.

Population Density Comparisons

The US averages about 94 people per mi² (36 per km²). Pinewood Falls, a town Sam knows well, covers about 12 mi² (31 km²) with a population of 28,000. That is 2,333 people per mi² (901 per km²) — dense for a small town but typical for an older American downtown area.


Related Calculators

Frequently Asked Questions

How many square kilometers are in a square mile?

One square mile equals 2.58999 square kilometers. For a quick estimate, multiply square miles by 2.6. This factor comes from squaring the linear mile-to-kilometer conversion (1.60934² = 2.58999).

How do I convert square miles to square kilometers?

Multiply square miles by 2.58999 to get square kilometers. For example, 50 mi² x 2.59 = 129.5 km². To convert back, divide km² by 2.59 or multiply by 0.3861.

How big is 1 square mile?

One square mile is a square measuring 1 mile (5,280 feet or 1.609 km) on each side. It equals 640 acres, 27,878,400 square feet, or 2.59 km². A section of land in the US Public Land Survey System is exactly 1 square mile.

What is a section of land?

A section is a unit of land in the US Public Land Survey System equal to exactly 1 square mile (640 acres or 2.59 km²). Townships are divided into 36 sections. This grid system was established by the Land Ordinance of 1785 and is visible in the rectangular field patterns across the Midwest.

How many acres are in a square mile?

One square mile contains exactly 640 acres. This is why farmland in the US is often sold in 40, 80, 160, or 320 acre parcels — they are neat fractions of a section (square mile). A quarter section (160 acres) was the standard homestead grant.