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# Metric Converter

Table of contents

What is the metric system?How to convert metric unitsAn example of conversion of metric unitsOther measurement units converterFAQs

Learn how to convert metric units by dividing and multiplying by ten with our handy tool: in a few steps, you will learn:

• How to convert metric units;
• The multiples and submultiples of metric units;
• A couple of examples of conversion of metric units;

and much more: jump right into the world of scientific measurements with Omni!

## What is the metric system?

The metric system is the world's most common system of measurement. The system is a relatively recent invention, if compared to the human need to measure things, and dates back to the eighteen century, when the age of enlightenment, in particular in France, brought some reason in the convoluted mess of separated (or not-so-separated) units used back then around Europe, and the world.

The metric system, being simple and intuitive, got adopted quickly by scientists worldwide, superseding feet, pounds, and other relatively weird units. In slightly more than a century, physicists, chemists, and engineers adopted meters, kilograms, and degrees (Celsius): you can still find imperial units in the United States, but even there, they are slowly disappearing.

The push to adopt metric units got a bit stronger when NASA inadvertently destroyed a probe en route to Mars because of a communication error between two components: one of them was talking in imperial units, the other in metric!

## How to convert metric units

To convert metric units, you only need to know a number: $10$! All the units that measure a single quantity (for example, length, mass, time) are connected by multiplication or division by $10$. This saves you a lot of time!

For each quantity, we define a primary unit, representative of the quantity. In a scientific environment, you will always be able to use that primary unit without anyone being phased by it. In the following sections, we will meet the metric units for the most commonly used quantities in science and engineering.

Each quantity, then, can be measured in various multiples and submultiples: to separate and identify them, we use prefixes. Prefixes quickly and uniquely identify the multiple of $10$ to use in the conversion. In the following table, you can see (almost) all the official prefixes used in the metric system. For the submultiples:

Prefix

Multiplier

Symbol

atto-

$10^{-18}$

$\mathrm{a}$

femto-

$10^{-15}$

$\mathrm{f}$

pico-

$10^{-12}$

$\mathrm{p}$

nano-

$10^{-9}$

$\mathrm{n}$

micro-

$10^{-6}$

$\mathrm{μ}$

milli-

$10^{-3}$

$\mathrm{m}$

centi-

$10^{-2}$

$\mathrm{c}$

deci-

$10^{-1}$

$\mathrm{d}$

And for the multiples:

Prefix

Multiplier

Symbol

deca-

$10^{1}$

$\mathrm{da}$

hecto-

$10^{2}$

$\mathrm{h}$

kilo-

$10^{3}$

$\mathrm{k}$

mega-

$10^{6}$

$\mathrm{M}$

giga-

$10^{9}$

$\mathrm{G}$

tera-

$10^{12}$

$\mathrm{T}$

peta-

$10^{15}$

$\mathrm{P}$

exa-

$10^{18}$

$\mathrm{E}$

To convert between metric units, follow these steps:

1. Consider the unit you are converting from: take note of the multiplier.
2. Find the multiplier of the unit you are converting into.
3. Divide the multipliers and multiply the result by the value of the first unit.
4. Change the prefix to the desired one.

## An example of conversion of metric units

To understand how to convert metric units, the easiest thing is to explore how this process works for a specific quantity, let's say, length. The primary unit for the length is the meter. The word meter comes from the Greek métron, "measure". The unit was created in 1793 by French scientists. Back then, the definition was "one ten-millionth of the distance on the Earth's surface from the north pole to the equator, on a line passing through Paris"; now we define the meter as the distance covered by light in $1/299792458$ of a second: talk about scientific improvement!

The submultiples of the meter are, in order of decreasing magnitude:

• The decimeter. $\mathrm{dm}$, equal to $0.1$ meters ($10^{-1}\ \mathrm{m}$);
• The centimeter, $\mathrm{cm}$, equal to $0.01$ meters ($10^{-2}\ \mathrm{m}$); and
• The millimeter, $\mathrm{mm}$, equal to $0.001$ meters ($10^{-3}\ \mathrm{m}$).

Passing in the realm of physics, we meet two other submultiples:

• The micrometer. $\mathrm{μm}$, equal to $0.000001$ meters ($10^{-6}\ \mathrm{m}$);
• The nanometer, $\mathrm{nm}$, equal to $0.000000001$ meters ($10^{-9}\ \mathrm{m}$);

Coming back, in the other direction, we meet:

• The kilometer. $\mathrm{km}$, equal to $1000$ meters ($10^{3}\ \mathrm{m}$);
• The megameter, $\mathrm{Mm}$, equal to $100000$ meters ($10^{6}\ \mathrm{m}$); and
• The gigameter, $\mathrm{Gm}$, equal to $100000000$ meters ($10^{9}\ \mathrm{m}$).

We rarely use the last two of them: the human experience is limited to the kilometer. In the direction of the submultiples, we rarely go smaller than the millimeter: our lives exist in six orders of magnitude!

## Other measurement units converter

Let's move outside of metric! Use the other tools of Omni for your conversion needs!

FAQs

### How do I convert from millimeters to kilometers?

To convert from millimeters to kilometers, you have to multiply by 0.000000001. To find this factor, follow these steps:

1. Consider the multiplier of the millimeter: 0.001 or 10^(-3).
2. Consider the multiplier of the kilometer: 1000 or 10^(3).
3. Divide the previously found factors: 0.001/1000 = 0.000001 or 10^(-6)

That's it: a kilometer equals a million millimeters!

### How many milligrams is 2 kg?

2 kg are equal to 2,000,000 milligrams. You can find this result by performing two conversions, passing through the metric primary unit of the mass, the gram:

1. 1 kg is equal to 1000 g; hence 2 kg = 2000 g.
2. 1 g is equal to 1000 mg: 2000 g = 2000000 mg.

You will never measure a milligram in your daily life, but the drugs you take contain active ingredients measured in that unit.

### How many liters is a cubic meter?

A cubic meter is equal to 1,000 liters. This means that, in a cubic meter, you can fit 1,000 cubes with a liter volume, ten per side.

Dividing a meter by ten gives you the first submultiple of the meter, the decimeter: a liter is equal to a cube decimeter.

### Is the kelvin a metric unit?

Yes: the kelvin is a metric unit of measurement! However, it's not a multiple or a submultiple of the celsius, the other metric unit for temperature: between the two scales, there is only an offset.

We say that the kelvin is an absolute scale of temperature, with zero corresponding to the absolute zero (the temperature at which thermal noises go to zero). Since the absolute zero lies at -273.15 °C, this is also the temperature offset between the scales:

T [°C] = T [K] + 273.15