Medication - Metric Conversions

Metric units and conversions for the calculation and administration of medication.

Basic Metric Units for drug administration

Quantity	Unit	Symbol
length	metre	m
mass	gram	g
volume	litre	l
time	second	s

Common Units of Measurement for drug administration

The various quantities of these units often have a prefix to make writing quantities more succinct. For example 0.000001g may be written as 1 mcg (or 1µg.)

Prefix	Symbol	Multiplication factor
mega	M	1,000,000
kilo	k	1,000
hecto	h	100
deka	da	10
unit	e.g. g, m, l or s	1
deci	d	0.1
centi	c	0.01
milli	m	0.001
micro	mcg or µ	0.000001

Converting a number from one metric unit to another involves moving the decimal place to the left or the right. To work out how many decimal places to move:

1. Identify the metric scale
2. Identify the two units in the problem
3. Count the number of units from the current unit to the desired unit
4. Move the decimal point the number of places from the given unit to the desired unit

Example 1 - Convert 0.1 grams to milligrams.
The decimal point is moved 3 places to the right - 0.1 g = 100 mg

Example 2 - Convert 375 millilitres to litres.
The decimal point is moved 3 places to the left - 375 ml = 0.375 l