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sq-miles to sq-km | Exact Decimal + Formula

1 Square Mile = 2.589988 Square Kilometer

Square miles to square kilometers is used for comparing country, state, and county sizes between US and international statistics.

About Square Mile and Square Kilometer

Square Mile (mi²)

A square mile is the area of a square with 1-mile sides, equal to 640 acres.

Where it's used: US county and city sizes, and large land statistics in imperial countries.

Square Kilometer (km²)

A square kilometer is the area of a square with 1-kilometer sides, 1,000,000 square meters.

Where it's used: Country, city, and national-park sizes; lake surface areas; and geographic statistics.

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Formula

km² = mi² × 2.58998811

To convert Square Mile to Square Kilometer, use the formula displayed above.

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Square Mile to Square Kilometer: Quick Reference Table

Square Mile Square Kilometer (Decimal) Fraction
0.001 mi² 0.00259 km² -
0.01 mi² 0.0259 km² 1/32 km²
0.1 mi² 0.258999 km² 17/64 km²
0.5 mi² 1.294994 km² 1 19/64 km²
1 mi² 2.589988 km² 2 19/32 km²
2 mi² 5.179976 km² 5 3/16 km²
5 mi² 12.949941 km² 12 61/64 km²
10 mi² 25.899881 km² 25 29/32 km²
25 mi² 64.749703 km² 64 3/4 km²
50 mi² 129.499405 km² 129 1/2 km²
100 mi² 258.998811 km² -
250 mi² 647.497027 km² 647 1/2 km²
500 mi² 1294.994055 km² -
1000 mi² 2589.98811 km² 2589 63/64 km²

mi² to km² Formula and Examples

Direct Formula km² = mi² × 2.58998811
Inverse Formula mi² = km² × 0.386102
Mental Math Shortcut

Multiply the value by roughly 2.6 to calculate the equivalent amount in your head.

Common Square Mile to Square Kilometer Calculations

  • 5 mi² = 12.949941 km²
  • 10 mi² = 25.899881 km²
  • 50 mi² = 129.499405 km²
  • 100 mi² = 258.998811 km²
  • 500 mi² = 1294.994055 km²

Precision & Practical Use

For example, 10 mi² = 25.899881 km² — roughly multiple unit increments.

Real-estate and construction figures are usually rounded to the nearest square foot or square meter. Keep 2–3 significant figures unless you're doing engineering takeoffs.

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Related Specialist Area Calculators & Niche Tools

Area conversions (square feet, square meters, acres, and hectares) are vital in real estate, landscaping, and construction. However, ordering materials requires converting flat surface measurements into material counts.

In home remodeling, flat wall and floor square footages are converted by paint coverage calculators (estimating paint gallons needed) or tile calculators (estimating tile counts, accounting for grout lines and a 10% waste factor). For roofing jobs, surface area is measured in roofing 'squares' (1 square = 100 sq ft). Landscapers use area calculators to estimate bulk mulch and topsoil volume in cubic yards. These specialized calculators bridge the gap between flat dimensional area and commercial material purchasing.

How to Convert Square Mile to Square Kilometer

How many square kilometers are in one square mile?
One Square Mile (mi²) equals 2.589988 Square Kilometer (km²). To convert square miles to square kilometers, multiply the square mile value by 2.589988.
How do I convert Square Mile to Square Kilometer?
Multiply your square mile value by 2.589988 to get the result in Square Kilometer: km² = mi² × 2.589988. For example, 5 mi² = 12.949941 km².
What is the formula for converting mi² to km²?
The conversion formula is km² = mi² × 2.589988. Use the calculator above for any value, and see the reference table below for common inputs from 0.001 to 1000.
Is there a quick mental estimate for mi² to km²?
Multiply the value by roughly 2.6 to calculate the equivalent amount in your head.
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