What Are Metric Conversions?
Every time you measure something — the length of a pencil, the volume of water in a bottle, or the area of a football pitch — you are using units. The metric system (officially called the International System of Units, or SI) gives us a consistent, logical set of units used by scientists and most of the world.
The beauty of the metric system is that it is entirely based on powers of 10. This means converting between units is simply a matter of multiplying or dividing by 10, 100, 1000, and so on — no complicated fractions required!
The International System of Units — a decimal-based system of measurement used globally in science. All units are related by powers of 10.
Think of metric prefixes like zoom levels on a map. Zooming out by a factor of 1000 turns metres into kilometres. Zooming in by a factor of 100 turns metres into centimetres. The scale changes, but the underlying reality stays the same.
Metric Prefixes — The Key to Every Conversion
Prefixes are attached to a base unit to make it larger or smaller. Once you know the prefixes, you can convert any metric measurement.
| Prefix | Symbol | Meaning (multiply base unit by…) |
|---|---|---|
| tera | T | 1 000 000 000 000 |
| giga | G | 1 000 000 000 |
| mega | M | 1 000 000 |
| kilo | k | 1 000 |
| hecto | h | 100 |
| (base unit) | — | 1 |
| centi | c | 0.01 |
| milli | m | 0.001 |
| micro | μ | 0.000 001 |
| nano | n | 0.000 000 001 |
| pico | p | 0.000 000 000 001 |
The most commonly used prefixes in MYP Sciences are kilo- (k), centi- (c), and milli- (m).
A handy memory trick for the order of common prefixes:
King Henry Died By Drinking Cold Milk
(Kilo, Hecto, Deca, Base, Deci, Centi, Milli)
Each step moves the decimal point one place.
The three most important base units you need to know are:
- Length → metre (m)
- Mass → kilogram (kg) (note: the base unit already has the prefix "kilo"!)
- Capacity → litre (L)
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