Square Mile (mi²)
A square mile is the area of a square one mile per side, equal to 640 acres or about 2.59 square kilometers.
Square miles describe city limits, national parks, and geographic regions in the US and UK.
Square Mile to Acre
Convert square mile to acre instantly. Type in either field — results update live.
Instant
Private
Free
Area Square Mile Acre
1 square mile = 640 acres
Unit
Unit
Conversion table
Selected mi² values converted to ac using the exact factor from this tool.
| mi² | ac |
|---|---|
| 0.01 | 6.4 |
| 0.1 | 64 |
| 1 | 640 |
| 2 | 1,280 |
| 3 | 1,920 |
| 5 | 3,200 |
| 10 | 6,400 |
| 20 | 12,800 |
| 50 | 32,000 |
| 100 | 64,000 |
| 1,000 | 640,000 |
How to convert
Exact conversion factors in both directions, plus a worked example.
1 mi² = 640 ac
1 ac = 0.0015625 mi²
To convert square mile to acre, multiply by 640.
To convert acre to square mile, multiply by 0.0015625.
Example: convert 10 mi² to ac
10 × 640 = 6400 ac
About these units
Short background on the units used in this conversion.
Acre (ac)
An acre is 43,560 square feet, or exactly 4,046.8564224 square meters — a traditional land measure.
Acres parcel farmland, suburban lots, and parks in the United States, UK, and several Commonwealth countries.
Frequently asked questions
How many acres are in one square mile?
One square mile equals 640 acres. Multiply your square miles value by 640 to convert to acres.
What is the conversion formula?
ac = mi² × 640The reverse is
mi² = ac × 0.0015625, using the same exact factors as this converter.Is this Square Mile to Acre converter private?
Yes. All calculations run locally in your browser. Nothing you type is sent to a server.
All square mile conversions
Jump to any area conversion starting from square mile — including the reverse direction and every other unit in our dataset.
acre (ac) → square mile (mi²)
square mile (mi²) → square meter (m²)square mile (mi²) → square kilometer (km²)square mile (mi²) → square centimeter (cm²)square mile (mi²) → square millimeter (mm²)square mile (mi²) → square micrometer (µm²)square mile (mi²) → square nanometer (nm²)square mile (mi²) → square decimeter (dm²)square mile (mi²) → square dekameter (dam²)square mile (mi²) → square hectometer (hm²)square mile (mi²) → hectare (ha)square mile (mi²) → are (a)square mile (mi²) → barn (b)square mile (mi²) → square mile (us survey) (mi² surv)square mile (mi²) → sectionsquare mile (mi²) → square yard (yd²)square mile (mi²) → square foot (ft²)square mile (mi²) → square foot (us survey) (ft² surv)square mile (mi²) → sabinsquare mile (mi²) → square inch (in²)square mile (mi²) → circular inch (circ in)square mile (mi²) → acre (us survey) (ac surv)square mile (mi²) → square rod (rd²)square mile (mi²) → square rod (us survey) (rd² surv)square mile (mi²) → square perch (perch²)square mile (mi²) → square pole (pole²)square mile (mi²) → square chain (ch²)square mile (mi²) → roodsquare mile (mi²) → township (twp)square mile (mi²) → homesteadsquare mile (mi²) → square mil (mil²)square mile (mi²) → circular mil (circ mil)square mile (mi²) → square nautical mile (NM²)square mile (mi²) → arpentsquare mile (mi²) → cuerdasquare mile (mi²) → plazasquare mile (mi²) → varas castellanas cuad (varas cast.)square mile (mi²) → varas conuqueras cuad (varas con.)square mile (mi²) → electron cross section (σₑ)