In programming I use values between 0 and 1 to represent percentages but the word percent means "one part in every hundred" (0-100). I've also heard people use permil for 'one part in every thousand" (0-1000).

In the past I've used the variable name perun in my code which is a made up word and most likely wouldn't make sense to others without being explained.

So my question: Is there a word that represents a value 0-1 similar to how percent represents a value 0-100?

  • 2
    What's wrong with "fraction"? I do use phrases like "the fraction of events in which this happens is about 0.5". Sep 1, 2011 at 5:16
  • 1
    You might be interested in the commentary on this closed question.
    – Kit Z. Fox
    Sep 1, 2011 at 11:50
  • 3
    proportion ?
    – GEdgar
    Sep 1, 2011 at 14:45
  • 1
    @MichaelMcGowan A proportion has to compare two actual things. He's talking about a quantity in terms of a notional unit. Feb 28, 2012 at 11:35
  • 4
    Even if there isn't a word for it, it doesn't mean the question is not a real question. It's a real question even if the answer is "no". Though in that case I'd expect the answer to offer alternatives that would work instead.
    – Mark Byers
    Jun 2, 2012 at 6:24

4 Answers 4


The word you are looking for is "fraction". A "fraction" is a number that represents the quotient of two numbers or a numeric quantity that is not a whole number. It can also simply mean a part broken off from the whole. Two online dictionaries give ".2" and "0.5" as examples of fractions.

  • While you are not wrong I was specifically asking for alternatives to the word "fraction".
    – rennat
    Mar 24, 2014 at 19:44
  • Clearly the use of "fraction" to describe "a small share" is valid in English, but in the context of mathematics would the use of "fraction" for a number like 0.2 still be valid? I would have thought not since it isn't a number with a numerator/denominator. That is why I think the OP was seeking alternatives to fraction. That said, I don't see any better alternatives.
    – Stephen
    Jul 6, 2017 at 17:00
  • @Stephen 0.2 and 1/5 are the same number. They're just different representations for that same value. Fractions are numbers that are not whole number. You have to qualify the word "fraction" to make it mean a form of representation, for example, "Express 1.2 as a fraction" or "What is the fractional representation of 1.2?". Jul 6, 2017 at 17:49
  • I don't understand your last sentence. I wouldn't think "fraction" is qualified in "Express 1.2 as a fraction." What do we mean to say a word is qualified? I would have expected it means that a word is modified by an adjective. In any case if "Express 1.2 as a fraction" were a problem in some elementary school math book, the implication is that the student would hear "as a fraction" and know that that means one specific form of representation, not two possible forms. Also, we wouldn't write that sentence if we thought 1.2 was already a fraction, which is what you are arguing.
    – Stephen
    Jul 6, 2017 at 20:05
  • @Stephen You can only "express" something as something that is a form of expression. I don't mean qualify in the grammatical sense but in the logical sense. For example, if you say "treat me like a peasant", the word "treat" qualifies "peasant" to refer to the way a peasant is typically treated, rather than any other inherent characteristic of a peasant. Similarly "Express 1.2 as a fraction" means to express the number 1.2 in the way fractions are typically expressed -- in the canonical form of representation for fractions. Jul 6, 2017 at 21:00

Perhaps, "decimal fraction" :

1.(arithmetic) The fractional part of a decimal number: the digits to the right of the decimal point.

Thus, a "decimal fraction" would refer to numbers smaller than one, but greater than zero

  • 1
    if he's looking for the non-interger part of a floating point number, then modulo could be used as well.
    – user12549
    Sep 1, 2011 at 5:21
  • "Decimal" seems incorrect here since there's no relation to "10" except being a base 10 system (which is true of percents as well).
    – A F
    Nov 10, 2015 at 4:14

For such a value there is no word (no common word, at least; note that you don't know it). What you described is a value drawn from the unit interval. I suggest you use "fraction" or "unit fraction", since fraction means part of a whole in one common meaning.

Aside: Percentages do not describe integers 0 to 100; one can have 250% and 1.1%. They describe a number represented visually by 100 times its value. Any normal number is a per-unit number; it is a number represented by 1 times the value (which is also 1 times 1 times its value, etc.). Hence "perunit" then isn't a usefully descriptive name.

  • You're right, you and @myqlarson both pointed out my error. I had meant that I'm looking for a word that relates to 0-1 like the word 'percent' relates to 0-100.
    – rennat
    Sep 1, 2011 at 6:05
  • 1
    unit interval appears to be correct: math.stackexchange.com/questions/2489/…
    – user12549
    Sep 1, 2011 at 10:45
  • 1
    When 10% is expressed instead as 0.1, that is called a proportion. So I claim it's wrong to say there is no such word. Feb 2, 2012 at 16:47

Technically, percent doesn't represent 0-100. It represents 0.01 to 1. The writing convention x% makes it seem like it represents 0-100.

If your rational floating point number is always going to be between 0 and 1, then it depends on the precision you are expecting. Between 0.00 and 1.00? Then percent is the word you are after. 0.000 and 1.000? per mil is the word you are after. Etc.

  • You're right, a percent isn't bound to the range 0-100. I did a poor job with my wording. What I was meaning was "percent" is to the range 0-100 as ____ is to the range 0-1
    – rennat
    Sep 1, 2011 at 6:03

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