This machine is inefficiency.

This machine is low efficiency.

Which one is correct, or what is the difference between them?

2 Answers 2


You should use:

This machine is inefficient.


This machine has a low efficiency.

Keep in mind that efficient is an adjective, and efficiency is a noun.


Both are wrong. Correct is:

"This machine is inefficient".
"This machine is low efficient". Or: "This machine's efficiency is low"

"Inefficient" is worse than "low efficient".
If a machine is low efficient, it's efficient enough to have a benefit - even if it is not much.
If a machine is inefficient, it means that the costs are higher than the earnings.

Ok, "to be low efficient" may be strange, but in my defense, when you have to deal mainly with scientific and engineering stuff, it seems to be acceptable - where I must admit that my references are mainly Asian authors:
Example 1
Example 2
Example 3
Example 4
Example 5
Example 6

  • 2
    Do you have an example of "low efficient" being used by a native English speaker? Efficient is an adjective, so "highly efficient" seems ok, but "low efficient" does not. The NGram doesn't appear to support "low efficient" as better than "low efficiency". books.google.com/ngrams/…
    – ColleenV
    Commented Oct 5, 2016 at 10:38
  • "The efficiency of this machine is low." would also work, wouldn't it?
    – miltonaut
    Commented Oct 5, 2016 at 11:13
  • 3
    "The machine is low efficient" doesn't sound correct. Commented Oct 5, 2016 at 11:15
  • 1
    "low efficient" sounds extremely unnatural to this US English speaker.
    – stangdon
    Commented Oct 5, 2016 at 14:21
  • 3
    If you are seeing a phrase like this in a technical articles with authors from non-English speaking countries, it's a hint that it may be a common mistake based on some characteristic of the author's first language. That's when it's good to know a little bit about English grammar, so you can tell what might just be technical jargon and what might be a mistake. Low is an adjective, but we expect an adverb to modify an adjective, not another adjective. That makes "low efficient" seem like it might be a mistake.
    – ColleenV
    Commented Oct 6, 2016 at 23:34

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