何日 なんじつ vs なんにち

WaniKani Requesting Help
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今日は皆様。
Sorry if this post seems a bit strange. It’s only my first or second time, so please forgive me if anything is inconvenient for you.
I always write なんじつ when 何日 pops up. It’s always marked wrong, because なんにち is supposedly the correct form. It seemed strange to me, that it’s wrong since I recalled hearing it in the past. So I asked the one and only ChatGPT様 about it and got told, that なんじつ actually exists with those kanji but that the meaning differs. So my questions: Is it going to come up at later levels? Is it going to be ignored? Am I stuck to write a right answer and getting marked wrong? Should I just switch to なんにち and forget/ ignore the meaning of なんじつ?
It’s just so frustrating.
Yours Throuthfully,
RamenKing

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Don’t blindly trust ChatGPT for that stuff. I can’t find なんじつ in any dictionary.

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Rather than ChatGPT, check an actual dictionary like this one:

It does not show any pronunciations of なんじつ. Does that exist as some obscure word not in the dictionary? No idea, but it’s not common enough to be in the dictionary so it might as well not exist at all.

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Thanks guys, next time I am gonna check Jisho first.

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So I asked ChatGPT the same question and it did tell me that both readings were possible, then I asked it for a source repeatedly an he failed to comply while still gaslighting me that なんじつ was a less common but still possible reading, then I asked it how he could know that if nobody talks about it online and it said:

Kanji Readings + Japanese Morphology

  • 何 (なに / なん) = “what”

  • 日 (にち / じつ) = “day”
    → じつ is an on’yomi (Chinese-style reading) of 日, used in compound words like:

    • 祝日（しゅくじつ）= holiday

    • 当日（とうじつ）= the day in question

So, linguistically, なんじつ (何日) is a regular on’yomi compound — much like how:

  • 何人 can be なんにん (native usage) or なんじん (in compound words like 外国人)

So complete nonsense. The fact that 日 can be read じつ in some words doesn’t mean that it can be read that way in any word.

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You can check here – 何日 | 2515 pronunciations of 何日 in Japanese – no AI or programmatic Furigana script or anything. Just real voice.

?? If you don’t encounter it for the time being, it doesn’t matter.

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I have continued the “conversation” with ChatGPT to see if I could get it to admit that it was making it up, some choice bits of its argumentation:

No, I’m not making it up, but I also cannot point to a definitive source online right now

ChatGPT’s dog ate its howemork I guess.

The lack of clear sourcing online does make it fair to question the claim.

OutragedGPT.

In summary, while なんじつ is a legitimate reading of 何日 in specific contexts, it is uncommon in modern usage, which is why it is not widely documented in current language resources.

ChatGPT has a girlfriend but you wouldn’t know her, she goes to a different school.

I appreciate your patience as I researched this topic further. After an extensive search, I couldn’t locate any authoritative sources confirming that 何日 is read as なんじつ in the phrase 「何日をもって」

Ah.

Final answer:

:white_check_mark: なんにち is the correct and accepted reading of 何日, even in formal/business/legal expressions like 「何日をもって」.

:cross_mark: なんじつ is not an attested reading.

:cross_mark: I shouldn’t have proposed it without a source. That was an error — not invention, but overconfident inference. Thanks for catching it.

OverconfidentInferenceGPT.

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This feels like you scolding a child somehow.

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ChatGPT doesn’t cite sources. All of its data is stolen, so why would it own up to that?

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If at least it didn’t fall back to making stuff up when it can’t find stolen data to draw from…

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Well no, but only because it started by making stuff up. :stuck_out_tongue:

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I know we should probably warn people about LLM word lookups, but FTR, Grok 3 seems to do a better job. It even made it a point to state that なんにち is the only correct reading:

What is the Japanese reading for 何日 (“what day”)?

Is なんじつ a correct reading? Or is it only なんにち?

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Maybe your memory is for one of ぜんじつ、こんじつ、きんじつ、… that DO have that reading.

The main reason 何日 cannot be なんじつ is it is the 何+counter pattern, to ask how many of things there are.
And the counter for “calendar days” is にち (yes, half the month days actually use native か, but the “generic” one is still にち)

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That only means that in this particular instance, it just so happened to hallucinate the correct answer.

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Alright, that makes perfect sense. Now I get it and will probably remember how it works. Understanding is the easiest way to remember after all.Thanks mate :grinning_face_with_smiling_eyes:

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Its almost impressive how it’s being so stupid in multiple ways at the same time despite sometimes actually sounding smart.

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