To convert units of one system into the other, multiply the number of units in column I by the equivalent factor opposite that unit in column II.

WEIGHT

1 gram	=	0.03527 avoirdupois ounce
1 gram	=	0.03215 apothecaries' ounce
1 kilogram	=	35.274 avoirdupois ounces
1 kilogram	=	32.151 apothecaries' ounces
1 kilogram	=	2.2046 avoirdupois pounds
1 grain	=	64.7989 milligrams
1 grain	=	0.0648 gram
1 avoirdupois ounce	=	28.3495 grams
1 apothecaries' ounce	=	31.1035 grams
1 avoirdupois pound	=	453.5924 grams

VOLUME (AIR OR GAS)

1 cubic centimeter (cm3)	=	0.06102 cubic inch
1 cubic meter (m3)	=	35.314 cubic feet
1 cubic meter	=	1.3079 cubic yard
1 cubic inch (in3)	=	16.3872 cubic centimeters
1 cubic foot (ft3)	=	0.02832 cubic meter

CAPACITY (FLUID OR LIQUID)

1 liter	=	2.1134 pints
1 liter	=	1.0567 quart
1 liter	=	0.2642 gallon
1 fluid dram	=	3.697 milliliters
1 fluid ounce	=	29.573 milliliters
1 pint	=	473.1765 milliliters
1 quart	=	946.353 milliliters
1 gallon	=	3.785 liters

TIME

1 millisecond = one thousandth (0.001) of a second	1 minute = 1/60 of an hour
1 second = 1/60 of a minute	1 hour = 1/24 of a day

TEMPERATURE
Given a temperature on the Fahrenheit scale, to convert it to degrees Celsius, subtract 32 and multiply by 5/9. Given a temperature on the Celsius scale, to convert it to degrees Fahrenheit, multiply by 9/5 and add 32. Degrees Celsius are equivalent to degrees Centigrade.
^* SEE: thermometer, Celsius for table.


PRESSURE

TO OBTAIN	MULTIPLY	BY
lb/sq in	atmospheres	14.696
lb/sq in	in of water	0.03609
lb/sq in	ft of water	0.4335
lb/sq in	in of mercury	0.4912
lb/sq in	kg/sq meter	0.00142
lb/sq in	kg/sq cm	14.22
lb/sq in	cm of mercury	0.1934
lb/sq ft	atmospheres	2116.8
lb/sq ft	in of water	5.204
lb/sq ft	ft of water	62.48
lb/sq ft	in of mercury	70.727
lb/sq ft	cm of mercury	27.845
lb/sq ft	kg/sq meter	0.20482
lb/cu in	g/ml	0.03613
lb/cu ft	lb/cu in	1728.0
lb/cu ft	gm/ml	62.428
lb/U.S. gal	gm/L	8.345
in of water	in of mercury	13.60
in of water	cm of mercury	5.3543
ft of water	atmospheres	33.95
ft of water	lb/sq in	2.307
ft of water	kg/sq meter	0.00328
ft of water	in of mercury	1.133
ft of water	cm of mercury	0.4461
atmospheres	ft of water	0.02947
atmospheres	in of mercury	0.03342
atmospheres	kg/sq cm	0.9678
bars	atmospheres	1.0133
in of mercury	atmospheres	29.921
in of mercury	lb/sq in	2.036
mm of mercury	atmospheres	760.0
g/ml	lb/cu in	27.68
g/sq cm	kg/sq meter	0.1
kg/sq meter	lb/sq in	703.1
kg/sq meter	in of water	25.40
kg/sq meter	in of mercury	345.32
kg/sq meter	cm of mercury	135.95
kg/sq meter	atmospheres	10332.0
kg/sq cm	atmospheres	1.0332

FLOW RATE

TO OBTAIN	MULTIPLY	BY
cu ft/hr	cc/min	0.00212
cu ft/hr	L/min	2.12
L/min	cu ft/hr	0.472

PARTS PER MILLION

Conversion of parts per million (ppm) to percent:

1 ppm = 0.0001%, 10 ppm = 0.001%, 100 ppm = 0.01%, 1000 ppm = 0.1%, 10,000 ppm = 1%, etc.

ENERGY

• 1 foot pound = 1.35582 joule
  
• 1 joule = 0.2389 Calorie (kilocalorie)
  
• 1 Calorie (kilocalorie) = 1000 calories = 4184 joules
  
• A large Calorie, or kilocalorie, is always written with a capital C.
  

pH
The pH scale is simply a series of numbers stating where a given solution would stand in a series of solutions arranged according to acidity or alkalinity. At one extreme (high pH) lies a highly alkaline solution; at the other extreme (low pH) is an acid solution containing 3.65 g of hydrogen chloride per liter of water. Halfway between lies purified water, which is neutral. All other solutions can be arranged on this scale, and their acidity or alkalinity can be stated by giving the numbers that indicate their relative positions. If the pH of a certain solution is 5.3, it falls between gastric juice and urine on the above scale, is moderately acid, and will turn litmus red.

Tenth-normal HCl	−1.00	Litmus is red in this acid range
Gastric juice	1.4
Urine	* 6.0
Water	7.00	Neutral
Blood	7.35–7.45	Litmus is blue in this alkaline range.
Bile	* 7.5
Pancreatic juice	8.5
Tenth-normal NaOH	13.00

^*These body fluids vary rather widely in pH; typical figures have been used for simplicity. Urine samples obtained from healthy individuals may have pH readings anywhere between 4.7 and 8.0.