The UK and the USA use something called the english system for sizes, volumes, weights, etc. Most of the rest of the world uses the metric system, officially known as SI. What do they know that we do not know? Simple answer: Metric (SI) is much easier. Ah, but we have all this investment in english system measures. Why for volume alone there is the ounce, the cup, the glass, the gill, the pint, the quart, the gallon (which comes in flavors: US / British Imperial), and on into the next week. Conversions can be a bit dicey, meaning break out a calculator or pencil and paper. Metric conversions are a slam dunk. We hope to show you that you already know most of metric: you just don't know that you know it!Start with length. Every classroom has a yardstick. But a yardstick is just a meter stick that shrunk a little. Add four inches to your yardstick and now it is a meter stick. See, you really do know how long a meter is. For a smaller unit, we divide the meter into 100 centimeters. (centi means 1/100). The centimeter is the thickness of a little finger (thickness - from front to back, not width). We can also divide the meter into 1 000 millimeters. A millimeter is about the thickness of 10 sheets of 22 pound copy bond. For road distances, 1 000 meters is a kilometer, and 10 kilometers is about 6 miles (6,2 if we need more precision). There are bigger and smaller prefixes. All told, there are 20 prefixes, but most of these are far outside of our everyday range. They are for particle physicists and cosmologists. For our everyday use, we need Mega meaning one-million (1 000 000), Kilo meaning one-thousand (1 000), no prefix at all meaning the basic unit, like meter, centi meaning one-one-hundreth (1/100), milli meaning one-one-thousanth (1/1 000), and micro meaning 0ne-one-millionth (1/1 000 000). Just five prefixes cover every size change in every unit we will need.These five prefixes are exactly the same for all measures. Notice that we used spaces to divide groups of 3 numerals instead of commas. This is because SI reserves the comma for its decimal point. Why you might well ask? Well, all this digital stuff is great, but on printouts the decimal point can be a single pixel, and it gets lost awfully fast. The comma holds up much better, and the space works really well on large or small numbers. Try the SI method; you will come to like it. The prefixes and units have official symbols. These are NOT abbreviations. They stay the same in all languages. Thus meter may become metre or something in arabic or korean script, but its symbol will always be m. The prefix symbols are as follow: Mega is capital M, Kilo officially k but it really should be capital K, centi c, milli m, and micro u. Actually micro is officially the greek letter mu, but you won't find it on your querty keyboard, so instead use u; u is close enough. Problem is 3 m prefixes -- poor planning. The fix is small m for milli which is less than 1, capital M for Mega which is greater than 1, and u for the smallest, micro.What about volume? The english system has ounce, glass/cup, pint, quart, and gallon. Larger measures such as peck, barrel, drum, etc. are really commercial. Metric has two: liter, which is a true volume measure, and cc (cubic centimeter) which is length cubed. There is only about 5% difference between a liter and a quart. The liter is slightly larger. For most purposes, you can consider the quart and liter as the same. The cc is a small cube one centimeter in each direction. A liter is a volume 10 centimeters (cm) x 10 cm x 10 cm, or multiplying 10 x 10 x 10, 1000 cc makes a liter. The english liquid ounce measure is about 30 cc. A glass or cup of something is about 8 ounces, one-fourth of a quart or liter, so about 250 cc. So a quart is (almost) a liter, a liter is (slightly more than) a quart. See, we do know the liter, and have been using it for years, and calling it a quart!Next there is weight. The SI weight unit is the kilogram. One kilogram is 2.2 pounds English. For rough conversion, double or half. So 10 kilograms is 20 pounds. For more accuracy, add 10% to the pounds. So 10 kilograms is 22 pounds. Suppose you weighed yourself at 200 pounds this morning. Well, now you are 90 kilograms. (Half less 10%.) Wow, improvement plus. Kilo stands for kilogram (shortened to kilo when the subject is clearly weight). One kilo is 1000 grams. 100 grams is 0,22 pounds, often a convenient shopping quantity for snacks, etc.Read more about pounds to kilograms For water or liquids that are mostly water, one ounce is roughly 30 grams.Other lingo includes k's (pronounced kays) or km's (pronounced kay ems) for road distances and klicks for distance in kilometers or speed in kilometers per hour. Thus 100 klicks is a speed of 100 kilometers per hour. Also kegs for kilograms. The speed of light, in kilometers per second, as it would be printed in proper SI: 299 792,458. Note that the decimal is a comma and the thousand separation a space. The period is only used to end the sentence, another advantage of using the comma as the decimal point. For the most part, the basic unit (liter, meter, etc.) is the official standard, but weight is an exception. The official unit would have been the gram, but it is too light to be a good standard, so the SI committee made the kilogram the official standard.Well you know the meter stick, and you know the liter. You can convert between pounds and kilograms. You can convert between miles and klicks. You know the five everyday prefixes: Mega (M) 1 000 000, Kilo (K) 1 000, centi (c) 1/100, milli (m) 1/1 000, and micro (u) 1/1 000 000. You have some lingo: k's, km's, kegs, klicks, and klicks per hour. You have learned meter (m) and liter (l) and cubic-centimeter (cc) and kilogram (kg). You are metric ready. Fly to Paris and start using metric immediately! For more info visit  pounds to kilograms