Which is more normal, "OK" or "オーケー"?

Question

Which is more normal in Japanese, "OK", or "オーケー", assuming either of them is in common usage?

I tried using the corpus on jisho.org, but the results were messed up by "OK" appearing in the English version. Tatoeba didn't get many matches for "オーケー", and many of them seemed to be false hits, and also got few hits for "OK" — is neither form commonly used in Japanese?

Answer 1

I assume by "normal in Japanese" you mean in writing, because "OK" can only be written Japanese.

I think this is best answered by a corpus search. The National Institute for Japanese Language and Linguistics provides an annotated version of the Balanced Corpus of Contemporary Written Japanese, giving the following results:

4241 results in total

• OK
  3849 results (91%)
• オーケー
  200 results (5%)
• オッケー
  100 results (2%)
• オーケイ
  43 results (1%)
• おｋ
  38 results (1%)
• オッケ
  8 results
• おーけー
  3 results

To do this yourself, go to http://nlb.ninjal.ac.jp/search/, search for オーケー taking you to http://nlb.ninjal.ac.jp/headword/N.00969/; go to the 基本 tab and expand 書字形.

Answer 2

They are both used commonly and we use either one depending on situation. Anyway, they are both normal. (I think ok is normal, but this is just an opinion-based answer.)

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I searched them with only Japanese pages on Google. The search results:

• OK - 118,000,000
• オーケー - 2,450,000

(I don't say this has credibility because Ok is including English sites even if I enabled that setting...)

Answer 3

The term "OK" is the casual word so there is no strict usage as far as casual usege.

"OK" is オーケー and "オーケー"　is OK!