Most countries in the world now use the metric system. Almost the only holdouts still using the old British Imperial system of weights and measures are the [[USA]] and [[Liberia]] (and [[Burma]] which uses yet another system). The [[United Kingdom]] and [[Canada]] (except the already fully metrified francophone [[Quebec]]) are in a curious state halfway between metric and Imperial units, and while many things are measured in metric, you will still often encounter miles, pints, feet and stone during your visit. The only units the two systems have in common are time units from second to century.
:'''-89 °C''' — '''''-129 °F''''' — Lowest temperature recorded on earth
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:'''-273.15 °C''' — '''''-459.67 °F''''' — Absolute zero
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For those who are not used to Metric thermometers, there are a few ways to think about it...
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'''Option 1''': From Metric (Celsius) to Fahrenheit, double the number and add 30. From Fahrenheit to Celsius, subtract 30 and divide in half. This is not exact and it won't work for much higher or lower temperatures, but it will be close enough to understand what the temperature is.
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'''Option 2''': A nice little poem to remember for Celsius...
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Zero is freezing.
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10 is not.
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20 is warm.
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and 30 is hot!
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'''Option 3''': For the mathematically inclined or those with a calculator: Fahrenheit=(C*1.8)+32. Celsius=(F-32)/1.8
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==Length and distance==
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<!--- need table of centimeters to inches equivalences appropriate for monthly rainfall amounts here -->
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* 1 inch (1") = 2.54 cm
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* 1 foot (1') = 30 cm
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* 1 mile = 1.6 km
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=== Comparisons ===
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* A credit card is about 0.75 mm (3/4 of a millimetre) thick
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* 1 cm (centimetre) is the width of an average fingernail.
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* Most adults are between 1.5 and 2 metres tall.
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* 1 km (Kilometre) takes about 15 minutes to walk.
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==Weight==
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* 1 kg = 2.2 pounds
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* 1 ounce = 28.54 grams
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* 1 pound = 454 grams
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For [[China]], the jing is almost exactly 500 grams.
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==Surface area==
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For small things, one might use square inches or square centimeters. There are about 6.5 cm<sup>2</sup> in one in<sup>2</sup>.
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For floor area of an apartment, there are about 11 square feet in one square meter.
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For large areas, there are about 2.5 acres in one hectare.
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== Volume ==
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The standard metric unit of volume is the litre.
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Many things, however, are measured in ml (millilitres) or equivalently in cc (cubic centimetres). Roughly, a teaspoon is 5 cc and a fluid ounce is 30 cc.
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In both the US and Imperial systems, 4 quarts = 1 gallon and 2 pints = 1 quart. However, the US units are smaller than Imperial counterparts. A US quart is 32 fluid ounces while Imperial is 40; a litre is in between at 35. A US gallon is 128 ounces or 3.78 litres, while an Imperial gallon is 160 ounces or 4.54 litres.
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For car and motorcycle engines, displacement might be given in cc or litres or cubic inches. 1000 cc or one litre is 61 cubic inches.
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=== Comparisons ===
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* 1 L of water weighs 1 kg. Since many liquids (milk, orange juice) are sold in litre containers it is easy to judge 1 L or 1 kg.
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* 1 L is equivalent to a cube 10 cm x 10 cm x 10 cm.
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* 1 Cubic m (1 m<sup>3</sup>) = 1000 litres. 1 m<sup>3</sup> of water weighs 1000 kg = 1 Tonne. Do not try to pick this up yourself!
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* In Europe, wine is usually sold in 750 mL (0.75 L) bottles (occasionally 700 mL or 1 L).
Most countries in the world now use the metric system. Almost the only holdouts still using the old British Imperial system of weights and measures are the USA and Liberia (and Burma which uses yet another system). The United Kingdom and Canada (except the already fully metrified francophone Quebec) are in a curious state halfway between metric and Imperial units, and while many things are measured in metric, you will still often encounter miles, pints, feet and stone during your visit. The only units the two systems have in common are time units from second to century.
58 °C — 136 °F — Highest temperature recorded on Earth
37 °C — 98.6 °F — Human body temperature
20 °C — 68 °F — Room temperature
0 °C — 32 °F — Water freezes
-18 °C — 0 °F — Ouch. Finnish people start to wear jackets.
-40 °C — -40 °F — Forty below zero!
-89 °C — -129 °F — Lowest temperature recorded on earth
-273.15 °C — -459.67 °F — Absolute zero
For those who are not used to Metric thermometers, there are a few ways to think about it...
Option 1: From Metric (Celsius) to Fahrenheit, double the number and add 30. From Fahrenheit to Celsius, subtract 30 and divide in half. This is not exact and it won't work for much higher or lower temperatures, but it will be close enough to understand what the temperature is.
Option 2: A nice little poem to remember for Celsius...
Zero is freezing.
10 is not.
20 is warm.
and 30 is hot!
Option 3: For the mathematically inclined or those with a calculator: Fahrenheit=(C*1.8)+32. Celsius=(F-32)/1.8
Length and distance
1 inch (1") = 2.54 cm
1 foot (1') = 30 cm
1 mile = 1.6 km
Comparisons
A credit card is about 0.75 mm (3/4 of a millimetre) thick
1 cm (centimetre) is the width of an average fingernail.
For small things, one might use square inches or square centimeters. There are about 6.5 cm^{2} in one in^{2}.
For floor area of an apartment, there are about 11 square feet in one square meter.
For large areas, there are about 2.5 acres in one hectare.
Volume
The standard metric unit of volume is the litre.
Many things, however, are measured in ml (millilitres) or equivalently in cc (cubic centimetres). Roughly, a teaspoon is 5 cc and a fluid ounce is 30 cc.
In both the US and Imperial systems, 4 quarts = 1 gallon and 2 pints = 1 quart. However, the US units are smaller than Imperial counterparts. A US quart is 32 fluid ounces while Imperial is 40; a litre is in between at 35. A US gallon is 128 ounces or 3.78 litres, while an Imperial gallon is 160 ounces or 4.54 litres.
For car and motorcycle engines, displacement might be given in cc or litres or cubic inches. 1000 cc or one litre is 61 cubic inches.
Comparisons
1 L of water weighs 1 kg. Since many liquids (milk, orange juice) are sold in litre containers it is easy to judge 1 L or 1 kg.
1 L is equivalent to a cube 10 cm x 10 cm x 10 cm.
1 Cubic m (1 m^{3}) = 1000 litres. 1 m^{3} of water weighs 1000 kg = 1 Tonne. Do not try to pick this up yourself!
In Europe, wine is usually sold in 750 mL (0.75 L) bottles (occasionally 700 mL or 1 L).
This is a usable article. It touches on all the major areas of the topic. An adventurous person could use this article, but please plunge forward and help it grow!