Measurements to live by

Sizing up the world around you, from square pegs to round holes

Weights and measures have been a matter for pharaohs, emperors, and kings to establish and of practical men and women to follow for thousands of years. The Egyptians based their system of measurement on the human body: the little finger to the thumb tip was considered a span, and two spans were the equivalent of one cubit, which was the distance from a person’s fingertips to the elbow. The mile was a Roman unit of measure: it came from the word “mille”, which stood for “1,000 paces”.

There are several legends to explain where the English unit of measure, the yard, came from. One is that it was the same length as King Henry I’s arm. Another is that it represented the distance from the tip of Henry’s nose to the end of his thumb. Yet another version suggests that it was inspired by the length of the arrows used by the King’s archers. In any case, the state’s role in setting standards has never been in doubt. For many centuries the weights and measures that Americans inherited from Britain were referred to as “the king’s standard.”

Americans have moved a fair way, however, from the Queen’s English and what has come to be known as the British Imperial System of weights and measures, and in the United States today, weights and measures are usually referred to by the name “U.S. Customary System.”

Most of the rest of the world, of course, follows the International (or Metric) System, which is a decimal system in which units of measurement increase by multiples of 10. First developed by ancient Hindo mathematicians and then embraced by the Arabs in the 10th century, the Metric System came into gradual use in Europe after 1100, and was officially adopted by the French in the late 1700s, about the time Louis XVI and Marie Antoinette faced the guillotine.

Led by the scientific and engineering communities, metrics are gradually winning wider acceptance in U.S. industry. Bu the day when the rulebook states that the proper height of a basketball hoop is 3.048 meters is still many years away.

Linear measure (use to measure lines and distances)

Customary U.S. units:

12 inches = 1 foot; 3 feet = 1 yard; 1,760 yards = 1 statute mile; 5 ½ yards = 1 rod; 40 rods = 1 furlong = 220 yards; 8 furlongs = 5,280 feet = 1 statute mile.

Metric units:

10 millimetres = 1 centimeter; 10 centimeters = 1 decimeter; 10 decimeters = 1 meter; 10 metres = 1 decameter; 10 decameters = 1 hectometer; 10 hectometers= 1 kilometer.

Customary U.S. units to metric units:

1 inch = 2.54 centimeters = 0.0254 meter

1 foot = 30.48 centimeters = 0.3048 meter
1 yard = 91.44 centimeters = 0.9144 meter
1 statue mile = 1.609,344 meters = 1.609344 kilometers.

Metric units to customary U.S. units:

1 centimeter = 0.3937 inch
1 meter = 3.28084 feet = 1.093613 yards
1 kilometer = 0.62137 mile

Mariners’ Measure: To measure distance, depth or speed at sea

Customary U.S. units:

6 feet = 1 fathom
1,000 fathoms (approximately) = 1 nautical mile
1 nautical mile = 1.151 statute mile
3 nautical miles = 1 league
60 nautical miles = 1 degree
1 knot = 1 nautical mile per hour

Square measure: Multiply length by width in units of the same denomination to find surface area.

Customary U.S. units:

144 square inches = 1 square foot
9 square feet = 1 square yard
30 ¼ square yards = 2 square rods
160 square rods = 1 acre
640 acres = 1 square mile

Metric units:

100 square millimeters = 1 square centimeter
100 square centimeters = 1 square decimeter
100 square decimeters = 1 square meter
100 square meters = 1 square decameter = 1 are
100 square decameters = 1 square hectometer
100 square hectometers = 1 square kilometer

Customary U.S. units to metric units:

1 square inch = 6.4516 square centimeters
1 square foot = 929.0304 square centimeters = 0. 09290304 square meter
1 square yard = 8.361, 2736 square centimeters = 0.83612736 square meter
1 acre = 4.046,8564 square meter = 0.404668545 square hectometer
1 square mile = 2.589.988.11 square meters = 258.998811 square hectometer = 2.58999911 square kilometers

Metric units to customary U.S. units:

1 square centimeter = 0.1550003 square inch
1 square meter = 1.550,003 square inches = 10.76391 square feet = 1.195990 square yards
1 hectare = 107.639,1 square feet = 11.959,90 square yards = 2.470538 acres = 0.003861006 square mile
1 square kilometer = 247.10538 acres = 0.3861006 square miles

Cubic measure:

Multiply length by breadth by thickness to find cubic content or volume

Customary U.S. units:

1.728 cubic inches = 1 cubic foot
27 cubic feet = 1 cubic yard

Metric units:

1,000 cubic millimeters = 1 cubic centimeter
1,000 cubic centimeters = 1 cubic decimeter
1,000 cubic decimeters = 1 cubic meter

Surveyors’ Measure: Use to measure the borders and dimensions of a tract of land

Customary U.S. units:

7.92 inches = 1 link
100 links = 1 chain
1 chain = 4 rods = 66 feet
80 chains = 1 survey mile = 5,280 feet

Surveyors’ Square measure: Multiply length by breadth to find surface area of land.

Customary U.S. units:

272 ¼ square feet = 1 square rod
16 square rods = 1 square chain
160 square rods = 10 square chains = 1 acre
640 acres = 1 square mile = 36 sections = 1 township

Liquid Measure: Use to measure a vessel’s capacity to hold liquids.

Customary U.S. units:

4 gills = 2 cups = 1 pint
2 pint = 1 quart
4 quarts = 1 gallon
31 ½ gallons = 1 barrel
2 barrels = 1 hogshead

Metric units:

10 milliliters = 1 centiliter
10 centiliters = 11 deciliter
10 deciliters = 1 liter
10 liters =  1 decaliter
10 decaliters = 1 hectoliter
10 hectoliters = 1 kiloliter

Apothecaries’ Fluid Measure: Use in mixing medicines.

Customary U.S. Units:

60 minims = 1 fluid dram
8 fluid drams = 1 fluid ounce
16 fluid ounces = 1 pint
2 pints = 1 quart
4 quarts = 1 gallon

Customary U.S. Units to Metric Units:

1 fluid once = 29,573528 millimeters = 0,02957 liter
1 cup = 236.588 milliliters = 0.236588 liter
1 pint – 473.176 milliliters – 0.473176 liter
1 quart = 946.3529 milliliters = 0.94663529 liter
1 gallon = 3.785,41 milliliters = 3.78541 liters.

Metric Units to customary US units:

1 milliliter = 0.0338 fluid ounce
1 liter = 33.814 fluid ounces = 4.2268 cups = 2.113 pints = 1.0567 quarts = 0.264 gallons.

Dry measure: Use to measure a vessel’s capacity to hold solids such as grain.

Customary U.S. units:

2 pints = 1 quart
8 quarts = 1 peck
4 pecks = 1 bushel

Customary U.S. units to metric units:

1 pint = 33,600 cubic inches = 0.551 liter
1 quart = 67.201 cubic inches = 1.101 liters.

Cooking measurement equivalents:

3 teaspoons = 1 tablespoon
1 tablespoon = 1/16 cup
2 tablespoons = 1/6 cup + 2 teaspoons
5 tablespoons = 1/3 cup + 1 teaspoon
6 tablespoons = 3/8 cups
10 tablespoons = 2/3 cup + 2 teaspoons
16 tablespoons = 1 cup = 48 teaspoons
2 cups = 1 pint
2 pints = 1 quart
4 quarts = 1 gallon.

Temperature conversions: To convert temperatures from Fahrenheit to Celsius, subtract 32 degrees and multiply by 5, then divide by 9. To go from Celsius to Fahrenheit, multiply by 9, divide by 5, then add 32 degrees.

Wood measure: To measure the volume of a pile of wood.

Customary U.S. units:

16 cubic feet = 1 cord foot = a wood pile 4 feet high by 4 feet wide by 1 foot long.
8 cord feet = 1 cord = a wood pile 8 feet long by 4 feet wide by 4 feet high.

Angular and circular measure: Use in surveying, navigating, astronomy, geography, reckoning latitude and longitude, and computing differences in time.

Customary U.S. units:

60 seconds = 1 minute
60 minutes = 1 degree
90 degrees = 1 right angle
180 degrees = 1 straight angle
360 degrees = 1 circle.

The lengths of a degree of longitude on the Earth’s surface at the Equator is 69.16 miles.

Troy Weight: Use in weighing gold, silver, jewels.

Customary U.S. units:

24 grains = 1 pennyweight
20 pennyweights = 1 ounce
12 ounces = 1 pound.

Avoirdupois weight:

Use for weighing heavy articles such as grain and groceries.

Customary U.S. units:

27 11/12 grains = 1 dram
16 drams = 1 ounce
16 ounces = 1 pound
100 pounds = 1 short hundredweight
20 short hundredweights = 1 short ton

Apothecaries’ Weight: For weighing medicines for prescriptions

Customary U.S. units:

20 grains = 1 scruple
3 scruples = 1 dram
8 drams = 1 ounce
12 ounce = 1 pound.

Metric weight: Use for measuring weights, distances, areas, and both dry and liquid capacities.

Metric units:

10 milligrams = 1 centigram
10 centigrams = 1 decigram
10 decigrams = 1 gram
10 grams = 1 decagrams
10 decagrams = 1 hectogram
10 hectograms = 1 kilogram
100 kilograms = 1 quintal
10 quintals = 1 ton

Mass and weight: Though they are not the same thing, mass and weight are identical in standard conditions (sea level on Earth), meaning that grams and other metric units of mass can be used as measures of weight or converted into customary units of weight.

Customary U.S. units to metric units:

1 ounce = 28.3495 grams
1 pound = 453.59 grams = 0.453569 kilogram
1 short ton = 907.18 kilograms = 0.907 metric ton

Metric units to customary U.S. units:

1 milligram = 0.000035 ounce
1 gram = 0.03527 ounce
1 kilogram = 35.27 ounces = 2.2046 pounds
1 metric ton = 2.204,6 pounds = 1.1023 short tons.

Egyptians

The Egyptians based their system of measurement on the human body: the little finger to the thumb tip was considered a span, and two spans were the equivalent of one cubit, which was the distance from a person’s fingertips to the elbow. Photo : Megan Jorgensen

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