How many square miles are in 1 acre?

1 ac equals 0.0015625 mi². This is an exact conversion factor defined by NIST.

How do I convert acres to square miles?

Multiply the value in ac by the conversion factor. For example, 10 ac = 0.015625 mi². Use our calculator above for instant results.

Is the acres to square miles conversion exact?

Yes, this conversion is mathematically exact based on the international definition of these units (NIST SP 811).

Can I convert acres to square miles offline?

Yes! OmniConvert runs entirely in your browser — no internet connection needed after the page loads. Your data never leaves your device, ensuring complete privacy.

What is the difference between acres and square miles?

Acres (ac) and Square Miles (mi²) are both units of area but belong to different measurement systems. 1 ac = 0.0015625 mi². Use the converter above to switch between them instantly.

Acres to Square Miles (ac → mi²) — Free Online Converter

ac → mi² Reference Table

ac	mi²
0.001 ac	0.0000015625 mi²
0.002 ac	0.000003125 mi²
0.003 ac	0.0000046875 mi²
0.004 ac	0.00000625 mi²
0.005 ac	0.0000078125 mi²
0.006 ac	0.000009375 mi²
0.007 ac	0.0000109375 mi²
0.008 ac	0.0000125 mi²
0.009 ac	0.0000140625 mi²
0.01 ac	0.000015625 mi²
0.02 ac	0.00003125 mi²
0.03 ac	0.000046875 mi²
0.04 ac	0.0000625 mi²
0.05 ac	0.000078125 mi²
0.06 ac	0.00009375 mi²
0.07 ac	0.000109375 mi²
0.08 ac	0.000125 mi²
0.09 ac	0.000140625 mi²
0.1 ac	0.00015625 mi²
0.2 ac	0.0003125 mi²
0.3 ac	0.00046875 mi²
0.4 ac	0.000625 mi²
0.5 ac	0.00078125 mi²
0.6 ac	0.0009375 mi²
0.7 ac	0.00109375 mi²
0.8 ac	0.00125 mi²
0.9 ac	0.00140625 mi²
1 ac	0.0015625 mi²
1.5 ac	0.00234375 mi²
2 ac	0.003125 mi²
2.5 ac	0.00390625 mi²
3 ac	0.0046875 mi²
3.5 ac	0.00546875 mi²
4 ac	0.00625 mi²
4.5 ac	0.00703125 mi²
5 ac	0.0078125 mi²
5.5 ac	0.00859375 mi²
6 ac	0.009375 mi²
6.5 ac	0.01015625 mi²
7 ac	0.0109375 mi²
7.5 ac	0.01171875 mi²
8 ac	0.0125 mi²
8.5 ac	0.01328125 mi²
9 ac	0.0140625 mi²
9.5 ac	0.01484375 mi²
10 ac	0.015625 mi²
11 ac	0.0171875 mi²
12 ac	0.01875 mi²
13 ac	0.0203125 mi²
14 ac	0.021875 mi²
15 ac	0.0234375 mi²
16 ac	0.025 mi²
17 ac	0.0265625 mi²
18 ac	0.028125 mi²
19 ac	0.0296875 mi²
20 ac	0.03125 mi²
25 ac	0.0390625 mi²
30 ac	0.046875 mi²
35 ac	0.0546875 mi²
40 ac	0.0625 mi²
45 ac	0.0703125 mi²
50 ac	0.078125 mi²
55 ac	0.0859375 mi²
60 ac	0.09375 mi²
65 ac	0.1015625 mi²
70 ac	0.109375 mi²
75 ac	0.1171875 mi²
80 ac	0.125 mi²
85 ac	0.1328125 mi²
90 ac	0.140625 mi²
95 ac	0.1484375 mi²
100 ac	0.15625 mi²
120 ac	0.1875 mi²
125 ac	0.1953125 mi²
130 ac	0.203125 mi²
140 ac	0.21875 mi²
150 ac	0.234375 mi²
160 ac	0.25 mi²
175 ac	0.2734375 mi²
180 ac	0.28125 mi²
200 ac	0.3125 mi²
225 ac	0.3515625 mi²
250 ac	0.390625 mi²
275 ac	0.4296875 mi²
300 ac	0.46875 mi²
350 ac	0.546875 mi²
400 ac	0.625 mi²
450 ac	0.703125 mi²
500 ac	0.78125 mi²
600 ac	0.9375 mi²
700 ac	1.09375 mi²
750 ac	1.171875 mi²
800 ac	1.25 mi²
900 ac	1.40625 mi²
1000 ac	1.5625 mi²
1200 ac	1.875 mi²
1250 ac	1.953125 mi²
1500 ac	2.34375 mi²
1750 ac	2.734375 mi²
2000 ac	3.125 mi²
2500 ac	3.90625 mi²
3000 ac	4.6875 mi²
4000 ac	6.25 mi²
4500 ac	7.03125 mi²
5000 ac	7.8125 mi²
6000 ac	9.375 mi²
7000 ac	10.9375 mi²
7500 ac	11.71875 mi²
8000 ac	12.5 mi²
9000 ac	14.0625 mi²
10000 ac	15.625 mi²
15000 ac	23.4375 mi²
20000 ac	31.25 mi²
25000 ac	39.0625 mi²
50000 ac	78.125 mi²
75000 ac	117.1875 mi²
100000 ac	156.25 mi²

Values based on NIST SP 811 conversion factors

Why Convert Acres to Square Miles?

Converting between acres (ac) and square miles (mi²) is one of the most common area conversions. Whether for engineering, cooking, travel, or science, knowing how to quickly convert ac to mi² saves time and prevents errors.

Area conversions between ac and mi² are critical for real estate valuation, agriculture, and urban planning. Farmers need accurate conversions when calculating crop yields, fertilizer application rates, or irrigation needs across hectares and acres. Homeowners and interior designers use area conversion for flooring, painting, and carpeting estimates to avoid costly material waste or shortages. In environmental science, deforestation rates and habitat protection zones are often reported in differing units depending on the region. A misunderstanding in area units can lead to significant financial discrepancies in property sales or incorrect resource allocation in land management projects.

How to Convert Acres to Square Miles

To convert acres to square miles, use the following formula:

mi² = ac × 0.0015625

Example: 1 ac = 0.0015625 mi²

For example, 5 ac = 0.0078125 mi², 10 ac = 0.015625 mi², and 100 ac = 0.15625 mi². For larger values, 1000 ac = 1.5625 mi². Conversely, 1 mi² = 640 ac. Our calculator above performs this conversion instantly with full precision — no rounding errors.

Common Mistakes to Avoid

Squaring the conversion factor: forgetting to square the linear conversion (1 ft = 12 in, but 1 sq ft = 144 sq in).
Confusing land units: mixing up acres and hectares.
Ignoring shape: area formulas differ for circles vs squares.

Pro Tips

Double check squares: Always ensure you're using square units (m²), not linear (m).
Estimation: An acre is roughly a football field (excluding end zones).
Paint calc: 1 gallon of paint covers approx 350-400 sq ft.

What is a Acre?

The acre is a unit of land area in the Imperial and US customary systems. One acre equals 43,560 square feet or approximately 4,047 square meters.

Acres are standard for measuring large plots of land, agricultural fields, and public parks in the US, UK, and former British Commonwealth countries.

What is a Square Mile?

An Imperial/US unit of area equal to 640 acres.

Used for large land areas in the US and UK.

Acres → Square Miles

Acres to Square Miles Formula