Which one of these examples is correct?

  1. Types of metal
  2. Types of metals

Do they have different meanings?


2 Answers 2


Both are correct, but types of metals is commonly used.
See the Google Ngram to see both usages

  • Plural is more common for practically all permutations of types / kinds / sorts / varieties of [NOUN], but to some extent it does depend on what specific [NOUN] is involved. For example, There are many varieties of fruit is just slightly more common than ...varieties of fruits. And with There are many forms of [NOUN], it's nearly always singular. There's probably no clear-cut reason for any variability, though. Aug 28, 2020 at 14:49

I would regard "types of metals" as wrong (Australian English). I believe it is also wrong in UK, but correct in US.

  • Your belief about UK usage is consistent with my experience as a UK resident.
    – mdewey
    Aug 28, 2020 at 13:26
  • You're correct that "types of metals" is not incorrect in the US. However, I would say that "types of metal" sounds much more colloquial to my ear, while "types of metals" sounds a more clinical or scientific. Aug 28, 2020 at 14:01
  • Regarding technical uses, in my technical editing (American English, British English, and Australian English), I would check only that the author is consistent throughout the research article. Both usages are clear and unambiguous. Aug 28, 2020 at 20:14

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