Metric and Imperial equivalents
This article is a travel topic
Most countries in the world now use the metric system.
Almost the only holdouts are the USA and Liberia (using a version of the old British Imperial system of weights and measures with peculiarly shrunken measures) and Burma (which uses yet another system).
However, in June 2011, the Burmese government's Ministry of Commerce began discussing proposals to reform the measurement system in Burma and adopt the metric system used by most of its trading partners.
The United Kingdom and Canada (except the already fully metricated and 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 stones during your visit. The only units the different systems have in common are time units from the second, through minutes, hours and days to centuries.
We use "=" signs below, but all are approximate. Note that there is spelling differences for the word "metre" and "litre" in American English, in which "metre" is called "meter" in the U.S., including "Kilometer" and "Litre" is called "Liter". In Addition, an "Tonne" is an "Metric Ton" to avoid confusion with the "Short Ton" which it's simply call an "Ton" in the US.
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
For China, the jing is almost exactly 500 grams.
 Surface area
For small things, one might use square inches or square centimeters. There are about 6.5 cm2 in one in2.
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.
The standard metric unit of volume is the litre.
Many things, however, are measured in mL (millilitres, also abbreviated outside of Wikitravel as ml) 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.
 Metric prefixes
1 mm = 1 / 1000 metres, 1 mg = 1 / 1000 g, 1 mL = 1 / 1000 Litres.
1 cm = 1 / 100 metres.
1 km = 1000 metres, 1 kg = 1000 grams.
 See also