In the United States, both systems are used: the traditional metric system of the United States and the metric system, especially in the fields of medicine, science and technology. In most other countries, the metric system is the primary measurement system. If you travel to other countries, you will see that road signs mark distances in kilometers and milk is sold in liters. People in many countries use words like “kilometer,” “liter,” and “milligram” to measure the length, volume, and weight of different objects. These units of measurement are part of the metric system.
Unlike the traditional metric system of the United States, the metric system is based on 10s. For example, a liter is 10 times larger than a deciliter, and a centigram is 10 times larger than a milligram. This idea of “10” is not present in the traditional metric system of the United States – there are 12 inches in one foot, and 3 feet in a yard … and 5,280 feet in a mile!
So, what if you need to find how many milligrams there are in a decigram? Or, what if you want to convert meters to kilometers? Understanding how the metric system works is a good start.
How to measure mg on a gram scale
What is metric?
The metric system uses units like the meter, the liter, and the gram to measure length, liquid volume, and mass, in the same way that the traditional metric system of the United States uses feet, quarters, and ounces.
In addition to the difference between the basic units, the metric system is based on 10s, and different measures for length include the kilometer, the meter, the decimeter, the centimeter, and the millimeter. Note that the word “meter” appears in all of these units.
The metric system also applies the idea that the units of the system increase and decrease by a power of 10. This means that a meter is 100 more than a centimeter, and that a kilogram is 1,000 times heavier than a gram. You will explore this idea later. For now, notice how this idea of “becoming 10 times bigger or smaller” is very different from the relationship between units of the traditional metric system in the United States, where 3 feet equals one yard, and 16 ounces equals 1 pound.
Length, mass, and volume
The following table shows the basic units of the metric system. Note that the names of all the metric units are formed from these three basic units.
In the metric system, the basic unit for length is the meter. A meter is a little longer than a yard, or a little more than three feet.
The basic metric unit for the mass is the gram. A paper clip of regular size has a mass of about 1 gram.
Among scientists, a gram is defined as the mass of water that would fill 1 cubic centimeter. You will notice that the word “mass” is used instead of the word “weight.” In science and technology, a distinction is made between weight and mass. The weight is the measure of the force of gravity of an object. For this reason, the weight of an object would be different if it is weighed on Earth or on the Moon, by the difference of gravitational forces. However, the mass of the object would be the same in both places because the mass measures the amount of substance in the object. As long as you plan to measure objects on Earth, you can use the words mass and weight indistinctly – but it’s worth noticing the difference!
Finally, the basic metric unit to measure a volume is the liter. A liter is a little bigger than a quarter.
|The handle of a shovel measures about one meter.||A paper clip weighs about one gram.||A medium container of milk contains about 1 liter.|
Although it is not common to switch between metric and traditional systems, it is sometimes useful to have a mental picture of how large or small the units are. The following table shows the relationship between both systems of some common units.
|Common measures in the metric and traditional systems|
|Length||1 centimeter is a little less than half an inch|
|1.6 kilometers are around 1 mile|
|1 meter measures around 3 fleas longer than 1 yard.|
|Dough||1 kilogram is a little more than 2 pounds.|
|28 grams is about 1 ounce|
|Volume||1 liter is a little more than 1 quart.|
|4 liters is a little more than a gallon.|
Prefixes in the metric system
The metric system is base 10. This means that each successive unit is 10 times larger than the previous one.
The names of the units of measure are formed by adding a prefix to the basic unit of measure. To know how big or small a unit is, look at the prefix. To know if the unit is to measure length, mass, or volume, you observe the base.
|Metric system prefixes|
|1,000 times larger than the base unit||100 times larger than the base unit||10 times larger than the base unit||base unit||10 times smaller than the base unit||100 times smaller than the base unit||1,000 times smaller than the base unit|
Using the table as a reference, you can see the following:
- One kilogram is 1,000 times larger than one gram (then 1 kilogram = 1,000 grams).
- One centimeter is 100 times smaller than one meter (then 1 meter = 100 centimeters).
- A decalitro is 10 times larger than a liter (then 1 decalitro = 10 liters).
Here we see a similar table that only shows the metric units for mass measurement, along with its size relative to one gram (the base unit). Common abbreviations for these metric units have also been included.
|Measuring mass in the metric system|
|1,000 grams||100 grams||10 grams||gram||0.1 gram||0.01 gram||0.001 gram|
Since the prefixes remain constant throughout the metric system, you can create similar tables for length and volume. The prefixes have the same meaning whether they are part of units of length (meter), mass (gram), or volume (liter).
Turning units up and down the metric scale
Converting units into the metric system requires knowledge of the prefixes and understanding how it works – and nothing more.
For example, you can find how many centigrams there are in a decagram using the table above. A decagram is larger than a centigram, so you would expect a decagram to be equal to several centigrams.
In the table, each unit is 10 times larger than the immediate unit on the right. This means that 1 decagram = 10 grams; 10 grams = 100 decigrams; and 100 decigram = 1,000 centigrams. So, 1 decagram = 1,000 centigrams.Once you begin to understand the metric system, you can use shortcuts to convert between different metric units. The size of the metric units increases 10 times when climbing the metric scale. The decimal system works in the same way: a ten is 10 times larger than a hundred; a hundred is 1o times bigger than a thousand, etc. By applying what you know about decimals to the metric system, converting between units is as simple as traversing decimal points.
Here we have the first problem above: How many milligrams are there in a decigram? You can recreate the order of the metric units as shown:
The question asks us to start with 1 decigram and convert it to milligrams. As shown above, milligrams are 2 links to the right of centigram. You can just move the decimal point two places to the right to convert to milligrams decigrammes: .
The same method can be used when you want to convert from a smaller unit to a larger one, as in the problem: Convert 1 centimeter to kilometers.
Note that instead of moving to the right, now we move to the left – so the decimal point should do the same .
|How many milliliters are there in 1 liter?
Show / Hide Answer
The metric system is an alternative system used in most countries, as well as in the United States. The metric system is based on combining one of a series of prefixes, including kilo-, hecto-, deca-, deci-, centi-, and milli-, with the base unit of measurements, such as the meter, the liter, or the gram. The units of the metric system are related to powers of 10, which means that each successive unit is 10 times larger than the previous unit. This makes the conversion from one metric measure to another a direct process and is usually as simple as moving the decimal point. It is always important, however, to consider the direction of the conversion. If you are converting a small unit to a larger unit, the decimal point has to be moved to the left (making your result smaller);