Conversion Constants
Contents
Converting from Imperial units
Converting from Geographic units
Using conversion constants
The following is a list of conversion constants that can be utilized in converting from one measurement system to another. The measurement system to be converted should be multiplied by the associated conversion constant. For example, to convert feet to centimeters, multiply feet by the conversion constant of 30.48 (27 feet x 30.48 = 822.96 centimeters).
Converting from Imperial units
Multiply |
by |
to obtain |
acres |
0.4046856 |
hectares |
acres |
43560.0* |
square feet |
acres |
4046.856 |
square meters |
acres |
0.0015625* |
square miles |
acres |
4840.0* |
square yards |
feet |
30.48* |
centimeters |
feet |
0.0003048* |
kilometers |
feet2 |
0.3048 |
meters |
feet (U.S. survey foot) |
0.304800609601** |
meters |
feet |
0.00018939394 |
miles |
feet |
304.8* |
millimeters |
square feet |
0.000022956 |
acres |
square feet |
929.0304* |
square centimeters |
square feet |
0.09290304* |
square meters |
square feet |
0.00000003587 |
square miles |
inches |
2.54* |
centimeters |
inches |
0.0254* |
meters |
inches |
0.000015782 |
miles |
inches |
25.4* |
millimeters |
inches |
0.027777778 |
yards |
square inches |
6.4516* |
square centimeters |
square inches |
0.00064516* |
square meters |
square inches |
645.16* |
square millimeters |
miles |
160934.4* |
centimeters |
miles |
5280.0* |
feet |
miles |
63360.0* |
inches |
miles |
1.609344* |
kilometers |
miles |
1609.344* |
meters |
vmiles | 1760.0* |
yards |
miles |
1.15077945 |
nautical miles3 |
square miles |
640.0* |
acres |
square miles |
27878400.0* |
square feet |
square miles |
2.589988110647 |
square kilometers |
yards |
914.4* |
millimeters |
yards |
91.44* |
centimeters |
yards |
0.0009144* |
kilometers |
yards |
0.9144* |
meters |
yards |
0.000568182 |
miles |
square yards |
0.000206611 |
acres |
square yards |
0.83612736* |
square meters |
square yards |
0.0000003228305 |
square miles |
Converting from Metric units
Multiply |
by |
to obtain |
centimeters |
0.03280839895 |
feet |
centimeters |
0.3937007874 |
inches |
centimeters |
0.00001* |
kilometers |
centimeters |
0.01* |
meters |
centimeters |
0.000006213711922 |
miles |
centimeters |
10.0* |
millimeters |
centimeters |
0.01093613298 |
yards |
square centimeters |
0.001076391042 |
square feet |
square centimeters |
0.15500031 |
square inches |
hectares |
2.471054073 |
acres |
hectares |
107639.1042 |
square feet |
kilometers |
1000000.0* |
millimeters |
kilometers |
100000.0* |
centimeters |
kilometers |
1000.0* |
meters |
kilometers |
1093.613298 |
yards |
kilometers |
3280.839895 |
feet |
kilometers |
39370.07874 |
inches |
kilometers |
0.6213711922 |
miles |
square kilometers |
247.1054 |
acres |
square kilometers |
10763910.42 |
square feet |
square kilometers |
0.386102158496 |
square miles |
meters |
100.0* |
centimeters |
meters |
3.280839895 |
feet |
meters |
3.280833333331 |
feet (U.S. survey foot) |
meters |
39.37007874 |
inches |
meters |
0.001* |
kilometers |
meters |
0.0006213711922 |
miles |
meters |
1000.0* |
millimeters |
meters |
1.093613298 |
yards |
square meters |
0.0002471054 |
acres |
square meters |
10.76391042 |
square feet |
square meters |
0.0000003861003 |
square miles |
millimeters |
0.1* |
centimeters |
millimeters |
0.003280839 |
feet |
millimeters |
0.03937007874 |
inches |
millimeters |
0.000001* |
kilometers |
millimeters |
0.001* |
meters |
millimeters |
0.0000006213711922 |
miles |
millimeters |
0.001093613298 |
yards |
square millimeters |
0.00001076391042 |
square feet |
Converting from Geographic units
Multiply |
by |
to obtain |
degrees |
1.111111111 |
grads |
degrees |
0.017453292 |
radians |
grads |
0.9* |
degrees |
grads |
0.015707963 |
radians |
radians |
57.2958 |
degrees |
radians |
63.6620 |
grads |
United State Survey Foot
In 1959, the directors of the National Bureau of Standards and the United States Coast and Geodetic Survey agreed on a redefinition of the inch-centimeter relationship. This redefinition defined 1 inch as equal to 2.54 centimeters, exactly, or 1 foot as equal to 0.3048 meters, exactly. However, their agreement stipulated that the older value for 1 meter equaling 39.37 inches, exactly, be retained for identifying the U.S. survey foot. One of the reasons for this retention was that the State Plane Coordinate Systems, which are derived from the national geodetic control network, are based on the relationship of 1 meter equaling 39.37 inches, exactly. The difference between these two values for the foot is very small, two parts per million, which is hardly measurable but not trivial when computational consistency is desired. Fundamental survey units, such as rods, chains, statute miles, acres, sections, and townships, all depend on the relationship of 1 meter equaling 39.37 inches, exactly. The following list represents the corrected values (or U.S. survey values), using the 39.37-inch conversion value:
Multiply |
by |
to obtain |
acres |
0.4046873 |
hectares |
acres |
10.0* |
square chains |
acres |
43560.0* |
square feet |
acres |
4046.873 |
square meters |
acres |
0.0015625* |
square miles |
acres |
160.0* |
square rods |
chains |
66.0* |
feet |
chains |
100.0* |
links |
chains |
20.11684 |
meters |
chains |
0.0125* |
miles |
chains |
4.0* |
rods |
square chains |
0.1* |
acres |
s quare chains |
0.04046873 |
hectares |
square chains |
4356.0* |
square feet |
square chains |
404.6873 |
square meters |
square chains |
0.00015625* |
square miles |
square chains |
16.0* |
square rods |
feet |
0.01515152 |
chains |
feet |
1.515152 |
links |
feet |
0.304800609601** |
meters |
feet |
0.00018939394 |
miles |
feet |
0.06060606 |
rods |
square feet |
0.00002295684 |
acres |
square feet |
0.000009290341 |
hectares |
square feet |
0.00000003587006 |
sections |
square feet |
0.0002295684 |
square chains |
square feet |
0.09290341 |
square meters |
square feet |
0.00000003587006 |
square miles |
square feet |
0.003673095 |
square rods |
square feet |
0.0000000009963907 |
townships |
hectares |
2.471044 |
acres |
hectares |
24.71044 |
square chains |
hectares |
107638.7 |
square feet |
hectares |
10000.0* |
square meters |
hectares |
0.003861006 |
square miles |
hectares |
395.3670 |
square rods |
links |
0.01* |
chains |
links |
0.66* |
feet |
links |
0.2011684 |
meters |
links |
0.000125* |
miles |
links |
0.04* |
rods |
meters |
0.04970960 |
chains |
meters |
3.280833333331 |
feet |
meters |
4.970960 |
links |
meters |
0.0006213699 |
miles |
meters |
0.1988384 |
rods |
square meters |
0.0002471044 |
acres |
square meters |
0.0001* |
hectares |
square meters |
0.0000003861006 |
sections |
square meters |
0.002471044 |
square chains |
square meters |
10.76387 |
square feet |
square meters |
0.0000003861006 |
square miles |
square meters |
0.03953670 |
square rods |
square meters |
0.000000010725 |
townships |
miles |
80.0 * |
chains |
miles |
5280.0* |
feet |
miles |
8000.0* |
links |
miles |
1609.347 |
meters |
miles |
320.0* |
rods |
square miles |
640.0* |
acres |
square miles |
258.9998 |
hectares |
square miles |
1.0* |
sections |
square miles |
6400.0* |
square chains |
square miles |
27878400.0* |
square feet |
square miles |
2589998.0 |
square meters |
square miles |
102400.0* |
square rods |
square miles |
0.027777778 |
townships |
rods |
0.25* |
chains |
rods |
16.5* |
feet |
rods |
25.0* |
links |
rods |
5.029210 |
meters |
rods |
0.003125* |
miles |
square rods |
0.00625* |
acres |
square rods |
0.002529295 |
hectares |
square rods |
0.0625* |
square chains |
square rods |
272.25* |
square feet |
square rods |
25.29295 |
square meters |
square rods |
0.000009765625* |
square miles |
sections |
27878400.0* |
square feet |
sections |
2589998.0 |
square meters |
sections |
1.0* |
square miles |
sections |
0.027777778 |
townships |
townships |
36.0* |
sections |
townships |
1003622400.0* |
square feet |
townships |
93239945.0 |
square meters |
townships |
36.0* |
square miles |
Additional Equivilants
width of township |
6 miles |
1 township |
36 sections |
1 mi2 (usually) |
1 section |
1 mi2 |
27,878,400 ft2 |
mean polar radius of Earth |
6373 km or 3960 mi |
Earth radius at Pole (Clarke Ellipsoid) |
6,356.6 km |
Earth radius at Equator (Clarke Ellipsoid) |
6,378.2 km |
* Constants are exact.
** A coordinate system in U.S. survey feet may be converted to a coordinate system in meters by scaling the system to a scale factor of 0.304800609601. An exact conversion can be accomplished by multiplying U.S. survey feet by the fraction 1200/3937.
1 A coordinate system in meters may be converted to a coordinate system in U.S. survey feet by scaling the system to a scale factor of 3.28083333333. An exact conversion can be accomplished by multiplying meters by the fraction 3937/1200.
2 The foot is one-third of the Imperial standard yard, which is defined to be 0.9144 meters, exactly. Thus the foot is defined as 0.3048 meters, exactly.
3 Represents the international nautical mile and also the U.S. nautical mile. The international nautical mile is defined to be 1852 meters, exactly. However, the U.K. nautical mile is defined to be the average distance on the earthís surface subtended by one minute of latitude, thus being 6080 feet, exactly, or 1853.184 meters, exactly.