Building the Basics: Percent

Percent (or per cent) is a way of expressing fractions out of 100.

Nurses and healthcare professionals use percent in medical research articles, which may state their findings as percentages of the total number of people investigated. For example “97% of patients reported having no side effects from the medication being trialed”. The components of medications and fluids are frequently expressed as percentages. For instance, a lotion may contain a certain percentage of active ingredient (e.g. 1% hydrocortisone), and an intravenous (IV) flask may contain 5% dextrose (5 parts of glucose per 100 parts of water) or 0.9% sodium chloride. If a patient is being given oxygen, the amount of oxygen is expressed as a percent. When breathing in atmospheric air, we are taking in 21% oxygen. 

Percent is written using this symbol: %. It goes after a number (whole or decimal). 30% is read 'thirty percent' and it means the same as 30/100 or 'thirty out of a hundred'. For more information, download the Percent Lesson PDF from the bottom of this page.

Percentages are related to fractions, decimals and ratios. These are some common conversions that are useful to learn:

1% 1/100 0.01
10% 10/100 = 1/10 0.1
20% 20/100 = 1/5 0.2
25% 25/100 = 1/4 0.25
33% 33/100 = 1/3 0.33
50% 50/100 = 1/2 0.5