How do you convert hectares to miles?

The question is also answered here: How many square centimeters are 1 square meter?

Name of the unit of area, A.Relationship to the SI unit square meter, m2Square meter (SI unit of area, A.)≡ 1 m × 1 m = 1 m2  Barn; b≡ 10-28 m2Circular mil; circular thou; circ mil≡ π / 4 mil2 ≈ 5,067 075×10-10 m2Square mil; square thou; sq mil≡ 1 mil2 = 6,4516×10-10 m2Circular inch; circ in≡ π / 4 in2 ≈ 5,067 075×10-4 m2Square inch; sq in; Square inches≡ 1 in2 = 6,4516×10-4 m2Board; bd≡ 1 in × 1 ft = 7.741 92 × 10-3 m2Square link; sq lnk≡ 1 lnk2 = 4,046 856 422 4×10-2 m2Square foot; sq ft; Square feet≡ 1 ft2 = 9,290 304×10-2 m2Square yard; sq yd; Square yards≡ 1 yd2 = 0.836 127 36 m2Cord≡ 192 bd = 1.486 448 64 m2Boiler Horsepower equivalent direct radiation; bhp EDR≡ 1 sq ft × 1 bhp / 240 BTU IT / h ≈ 12,958 174 m2Square rod; pole; perch; approx2≡ 25,292 852 64 m2Are; a≡ 100 m2Square chain; sq ch≡ 1 ch2 = 404.685 642 24 m2Dunam≡ 1000 m2Rood; ro≡ 1/4 ac = 1011.714 105 6 m2Acre; ac≡ 10 sq ch = 4840 sq yd = 4046.856 422 4 m2Hectares; Ha≡ 10,000 m2 = 0.01 km2Yardland≡ 30 ac = 1.214 056 926 72 × 105 m2Hide≡ 100 ac = 4.046 856 422 4 × 105 m2Square kilometre; km2≡ 106 m2Square mile; section; sq mi; mi2; Square mile≡ 2,589 988 110 336×106 m2Square Statute Mile; square US Survey mile; sq mi≈ 2,589 998×106 m2Township≡ 36 sq mi (US) ≈ 9.323 994 × 107 m2Barony≡ 4000 ac = 1.618 742 568 96 × 107 m2

A surface is measured in the following units:
1 square kilometer (km2) corresponds to 100 hectares or a square with a side length of 1 km.
1 hectare (ha) corresponds to 100 ares; 1 Ar (a). One ar is equal to 100 square meters.
1 square meter (m2) corresponds to 100 dm2 or a square with a side length of 1 m.
1 square decimeter (dm2) corresponds to 100 square centimeters.
1 square centimeter (cm2) corresponds to 100 square millimeters.
1 square millimeter (mm2).

Square millimetersmm² 1 mm²=0.000001 m²
Square centimeterscm² 1 cm² = 0.0001 m²
Square decimetersdm² 1 dm²=0.01 m²
square meters 1 =0.01 a
Ara 1 a=100 m²
HectaresHa 1 Ha=10,000 m²
Square kilometrekm² 1 km²=1,000,000 m²