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SI* (MODERN METRIC) CONVERSION FACTORS
APPROXIMATE CONVERSIONS TO SI UNITS APPROXIMATE CONVERSIONS FROM SI UNITS

Symbol When You Know Multiply By To Find Symbol Symbol When You Know Multiply By To Find Symbol


LENGTH

LENGTH
in inches 25.4 millimeters mm mm millimeters 0.039 inches in
ft feet 0.305 meters m m meters 3.28 feet ft
yd yards 0.914 meters m m meters 1.09 yards yd
mi miles 1.61 kilometers km km kilometers 0.621 miles mi

AREA

AREA
in2 square inches 645.2 square millimeters mm2 mm2 square millimeters 0.0016 square inches in2
ft2 square feet 0.093 square meters m2 m2 square meters 10.764 square feet ft2
yd2 square yards 0.836 square meters m2 m2 square meters 1.195 square yards ac
ac acres 0.405 hectares ha ha hectares 2.47 acres mi2
mi2 square miles 2.59 square kilometers km2 km2 square kilometers 0.386 square miles  

VOLUME

VOLUME
fl oz fluid ounces 29.57 milliliters ml ml milliliters 0.034 fluid ounces fl oz
gal gallons 3.785 liters l l liters 0.264 gallons gal
ft3 cubic feet 0.028 cubic meters m3 m3 cubic meters 35.71 cubic feet ft3
yd3 cubic yards 0.765 cubic meters m3 m3 cubic meters 1.307 cubic yard yd3
NOTE: Volumes greater than 1000 l shall be shown in m3

MASS

MASS
oz ounces 28.35 grams g g grams 0.035 ounces oz
lb pounds 0.454 kilograms kg kg kilograms 2.202 pounds lb
T short tons (2000 lb) 0.907 megagrams Mg Mg megagrams 1.103 short tons (2000 lb) T

TEMPERATURE (exact)

TEMPERATURE (exact)
F Fahrenheit temperature 5(F-32)/9 or (F-32)/1.8 Celcius temperature C C Celcius temperature 1.8C +32 Fahrenheit temperature F

ILLUMINATION

ILLUMINATION
fc foot-candles 10.76 lux l lx lux 0.0929 foot-candles fc
fl foot-Lamberts 3.426 candela/m2 cd/m2 cd/m2 candela/m2 0.2919 foot-Lamberts fl

FORCE and PRESSURE or STRESS

FORCE and PRESSURE or STRESS
lbg poundforce 4.45 newtons N N newtons 0.225 poundforce lbf
psi poundforce per square inch 6.89 kilopascals kPa kPa kilopascals 0.145 poundforce per square inch psi
(Revised August 1992)


*SI is the symbol for the International System of Units. Approximate rounding should be made to comply with Section 4 of ASTM E380.

The use of SI units is encouraged with Part VI. Future editions of Part VI will use only SI units. The conversions will be based primarily on AASHTO guides. Specific conversion of standards will be subjected to the FEDERAL REGISTER rulemaking process.

U.S. Department of Transportation
Federal Highway Administration