How do I say that something was decreased and became X times less? In a sentence like: The new file is 20K while the old file was 100K, that's a decrease in 5 times? Or: The file was 100K and it decreased by 5 times, becoming only 20K?

For instance, I found this topic where someone said:

"Decreased by 8 times" doesn't mean anything to me at all.

What are the most used and naturally sounding constructions for this types of sentences?

4 Answers 4


The other answers are correct, but the common English expression that is the actual equivalent of what you are referring to is

The file size decreased by a factor of five.


I suggest that quick and easily understood ways of saying this are

The file size decreased by 80%, from 100k to just 20k.

The file size decreased to 20% of its original size, from 100k to just 20k.

The file size decreased to one-fifth of its original size, from 100k to just 20k.

  • Is it fine and commonly used to attribute the decrease (as a noun) that happened, rather than attributing the process? I suppose "that was a (an?) 80% decrease" is fine to say. Or it's common only to use adjectives (like huge/tremendous/significant decrease) but not specific values? Jan 29, 2014 at 17:22
  • If the numbers are important, use the numbers. If you want to leave it vague, use adjectives. Jan 29, 2014 at 17:32

It makes sense to say that something "decreased by 80%" or "decreased by 1/3". I don't know what "decreased by 8 times" would mean. Decreased by 8 times what? When someone says that it "increased by 3 times" they mean by 3 times the original value, so if it used to be, say, 100 -- well, sometimes they mean it is now 3 times the original value, i.e. 300, other times they mean that it added 3 times the original value, so it is now 400. But "decreased by 8 times"? If it used to be 100, is it now negative 700? Possible, I guess, depending on what it is we're measuring.

It is reasonable to say that something "decreased 7 times", meaning that there were 7 occasions on which it decreased. Like, "While it looks like I got raises every year on paper, my salary has really decreased 7 times in the last 12 years if you adjust for inflation."


Indeed, if something decreases (by) a number of times, I have a hard time understanding what is meant exactly. It is a lot more informational to use a construction like:

The file size decreased by 80%.

The problem with "decreased (by) 5 times" is that nobody knows how much a one-time decrease is. In the case of your file size, it decreased to one fifth of the original size. "Decreasing 5 times" would indicate that it somehow decreased in size 5 times, first from 100 to 84 (??), and so on. But you would never say it decreased once of it went from 100 to 84, since that 1-time decrease only means "16" in case of an 80% decrease :)

  • Yeah, I figured where's the problem. Interestingly, in Russian, it's perfectly fine (and it's the most commonly used way to say!) to decrease something by X times, which means that if you increase the object back X times, it would become the original size. But the phrase only starts making sense when X > 1 (at least 1.1), a one-time decrease is meaningless as well. Go figure! Jan 29, 2014 at 17:34

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