Word Use: Percent vs. Percentage
5% or 5 percentage? Lower %? What is the Correct Use?
Are Percent and Percentage Synonyms? Are they Interchangeable?
Unfortunately, no. Percent and percentage are two of the most misused terms in the English language, even by English and math professors who should know better.
Fortunately, it 's easy to learn when you should use percent vs. percentage. A percent is a number; a percentage is an amount.
Did you know there was a difference between these two words before reading this article?
Percent
A "percent" is always a specific number, amount, or quantity, such as 5 percent or 100 percent.
"Percent": Usage rules:
 Never spell out the number in front of the word "percent", even if you would normally spell it out. For example, "5 percent" is correct, not "five percent".
 Always use one space between the number and "percent". For example, "5 percent" is correct, "5percent" is incorrect.
 Spell out "percent" as one word, never "per cent" or "per ¢" or "%".
"Percent": Exceptions to the Usage Rules (Pesky, but Necessary)
 It's okay to use the symbol "%" in tables and highly technical materials where the term comes up repeatedly.
 Or, if it is mandated in your house style guide.
 Or, if it is used directly in or on a product, such as a user interface, that you are documenting.
Percentage
A percentage is never a specific amount, such as "5 percentage" or "12 percentage", it is a generalization or trend in specific amounts.
"Percentage": Examples
For example:
 ...a greater percentage of students...
 ...test results showed higher percentages in most subjects, sometimes up to 20 percent higher...
 ...we're looking for a lower percentage of...
 ...rates went down by a large percentage...
 ...buy it now before the discount percentages disappear...
Percent and Percentage Usage Rules
Correct
 Incorrect
 Reason


a higher percentage
 90 percentage
 Never use or spell out a specific number in front of the word "percentage", even if you would normally. If the number is significant, use it with "percent" instead.

5 percent
 5 percentage
 Never use percentage with a specific number in front of it, always use "percent". (See above also.)

a lower percentage
 a lower percent
 Always use one space between the amount adjectives and the word "percentage".

percentage
 per centage, %age, per ¢age, and other abbreviations
 Spell out "percentage" as one word; don't abbreviate in formal text

"Percentage": Exceptions to the Usage Rules
It's okay (in fact necessary) to violate these usage rules for "percentage" in some cases, such as:
 If it is mandated in your house style guide. (Though I would lobby to get it changed to match standard usage as documented here.)
 Or, if it is used directly in or on a product, such as a user interface, that you are documenting.
Bonus Video: How to Calculate Percentages Like a Genius
So, Then What's a "Percentile"?
Percentile, by the way, is also called "centile".
If you have a hundred thingspeople or pieces of candy, for examplea "percentile" marks the boundary between any two intervals in that group. You can have more or fewer things than 100, you just mathematically make it equal to a fraction of 100 and multiply that number by the number of things you DO have.
Here's how the experts define it:
"the value of the statistical variable that marks the boundary between any two consecutive intervals in a distribution of 100 intervals each containing one percent of the total population  called also centile."
_{"percentile." Webster's Third New International Dictionary, Unabridged. MerriamWebster, 2002. }
_{http://unabridged.merriamwebster.com}
_{ (16 Jan. 2012)}
Follow the same usage rules as for "percent", above.
Questions & Answers
Comments
Great realization...for many.. it cleared a few doubts if mine though...great...
Thanks and well done
Not a problem. I didn't mean to publicly embarrass you  I slip up very easily, and even at 53 years of age I am often shocked my some term or phrase I've been using for years, which turns out to have a significantly different shade of meaning than I had thought all my life. I discovered only recently that I have been using "factoid" slighly wrongly, and therefore saying a few silly things. I had always thought it meant "some minor fact, easily stated"  a valid, true, fact. But in fact its PRINCIPAL meaning is in reference to a madeup spurious statement presented as "fact". Some dictionaries allow my meaning, but only as a secondary connotation. And I see now that using the term in many situations has reversed my intended meaning. And ... that's a fact.
Your definition of "percentile" is roughly correct, though poorly articulated and difficult to parse. But both your examples are wrong.
If a score is 80 percent higher than all other scores in a group then it will be the top score  by a very large margin, and therefore "in the 99th percentile" (we generally do not refer to a "100th percentile").
The second example involves what we call "qualitative (nonnumeric) data". When the points of data cannot be ranked against each other on a scale, as with numeric "scores", the term "percentile" is meaningless. In the example you give, it is correct (only) to say that 12% of the candies are red.
Here's how one computes percentile: List (i.e., rank) all your points of data from smallest to largest. Now divide them up into 100 equalsized groups by placing 99 dividers in appropriate places along the scale. The first group is the 0th percentile; the next group is the 1st percentile, all the way up to the 100th group, which is the 99th percentile. If your score is in the 80th percentile in a class of 100 students with no two scores the same it is higher than 80 other students' scores and lower than 19 others. But you have no information about how much higher or lower you have scored than the others.
What if the number of points is not a multiple of 100, or when you divide them up, some data in the group above a divider have the same value as those below? No matter. There are rules of thumb for these, but the basic idea is "do the obvious thing". Being "in the nth percentile" always means "at least as high as n% of the other points".
"Quartiles" are obtained in a similar fashion by dividing the data into four parts of equal size. The "median" is the point of division between the 49th and 50th percentiles.
Remember, quartiles and percentiles are GROUPS of data (or individuals), which is why we say "in the ... ". On the other hand, the median is only a single value, so we do not say "in the median", but "above", "below" or "at" the median. Above the median you are in the top half of the class; below it you are in the bottom half.
I wanted to vote, but didn't because there was no option for 'Not sure how I've used them in the past, but will go back to look'. I may have used them on Hubs here, but will go back and look (and modify as needed). I know I've used the words elsewhere, and will be sure to think conciously about using them properly in the future.
Good writeup, it is clear and wellexplained.
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