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Table C— 5. Conversion Factors - British to Metric Units of Measurement 



The following conversion factors adopted by the Bureau of Reclamation are those published by the 

 American Society for Testing ana Materials (ASTM Metric Practice Guide, January 1964) except that addi- 

 tional factors (*) commonly used in the Bureau have been added. Further discussion of definitions of 

 quantities and units is given on pages 10-11 of the ASTM Metric Practice Guide. 



The metric units and conversion factors adopted by the ASTM are based on the "International System 

 of Units" (designated SI for Systeme International d'Unites), fixed by the International Committee for 

 Weights and Measures; this system is also known as the Giorgi or MKSA (meter-kilogram (mass)-second- 

 ampere) system. This system has been adopted by the International Organization for Standardization in 

 ISO Recommendation R 31. 



The metric technical unit of force is the kilogram-force; this is the force which, when applied to a 

 body having a mass of I kg, gives it an acceleration of 9.80665 m/sec/sec, the standard acceleration of 

 free fall toward the earth's center for sea level at 45 deg latitude. The metric unit of force in SI units 

 is the newton (N), which is defined as that force which, when applied to a body having a mass of I kg, gives 

 it an acceleration of I m/sec/sec. These units must be distinguished from the (Inconstant) local weight of 

 a body having a mass of I kg; that is, the weight of a body is that force with which a body is attracted to 

 the earth and is equal to the mass of a body multiplied by the acceleration due to gravity. However, because 

 it is general practice to use "pound" rather than the technically correct term "pound-force," the term 

 "kilogram" (or derived mass unit) has been used in this guide instead of "kilogram-force" in expressing the 

 conversion factors for forces. The newton unit of force will find increasing use, and is essential in SI 

 units. 



QUANTITIES AND UNITS OF SPACE 



Mu I t i p I y 



By 



LENGTH 



Mil. . 

 I nches 



# 



Yards . . . . 

 Mi les (statute) 



25.4 (exactly) . . 



25.4 (exactly) . . 



2.54 (exactly)* . . 



30.48 (exactly) . . 

 0.3048 (exactly)* 

 0.0003048 (exactly)* 



0.9144 (exactly) . . 



1,609.344 (exactly)* . . 



1.609344 (exactly) . 



Micron 



Mi I I imeters 



Centimeters 



Cent imeters 



Meters 



Ki lometers 



Meters 



Meters 



Ki I ometers 



AREA 



Square Inches 

 Square feet . 



Square yards 

 Acres 



Square mi les 



6.4516 (exactly) . 

 929.03 (exactly)* . 

 0.092903 (exactly) 

 0.836127 . . . 

 0.40469* . . . 

 4,046.9* .... 

 0.0040469* . . . 

 2.58999 . . . 



Square centimeters 

 Square centimeters 

 Square meters 

 Square meters 

 Hectares 

 Square meters 

 Square kilometers 

 Square kilometers 



VOLUME 



Cubic inches 

 Cubic feet 

 Cubic yards . 



16.3871 

 0.0283168 

 0.764555 



Cubic centimeters 

 Cubic meters 

 Cubic meters 



CAPAC I TY 



Fluid ounces (U.S. ) 

 Liquid pints (U.S. ) 

 (Juarts (U.S.) . . 

 Gal Ions (U.S.) . . 



Gal Ions (U.K.) 



Cubic feet 

 Cubic yards 

 Ac re- feet 



29.5737 

 29.5729 

 0.473179 

 0.473166 

 9,463.58 . . 



0.946358 



3,785.43* . . 



3.78543 . . 



3.78533 . . 



0.00378543* 



4.54609 . . 



4.54596 . . 



28.3160 . . 



764.55* . . 



1,233.5* . . . 



.1,233,500* . . . 



Cubic centimeters 



Mi I I i I iters 



Cubic decimeters 



Liters 



Cubic centimeters 



Liters 



Cubic centimeters 



Cubic decimeters 



Liters 



Cubic meters 



Cubic decimeters 



Liters 



Liters 



Li ters 



Cubic meters 



Liters 



C-41 



