In several sources it's mentioned that a SMALL TSU doubles consonants.

My problem is, some websites give almost identical examples with:

っ/ッ + (S, T, C, K, G, B, P)

But what about the others?:

っ/ッ + (M, N, V, W ...)

When I use some online converter(Kana>Romaji), they double all of them.

So, does a SMALL TSU double all consonants or not? And if not, in which cases?

Thank you for your help!


A small tsu (sokuon) geminates (doubles) the following consonant. In native vocabulary, only unvoiced consonants can be geminated. This includes the さ, た, か, and ぱ rows. A double n as in おんな is not really pronounced the same way as *おっな would be if it were a word.

In loanwords that require gemination of other consonants, N tends to use ン, M uses ン or ム, W uses ウ, and others use the -u form of their row. Some examples are:

  • homemade → ホームメード
  • comma → コンマ
  • whistleblower → ホイッスルブロウワー
  • role-playing game → ロウルプレイングゲーム

Some loanwords do use the sokuon where native words would not, such as:

  • big → ビッグ
  • badge → バッジ

The important thing is that these are all loanwords. You generally won't see such examples written in hiragana, though the sokuon is used the same way in either writing system.

You may also see the small tsu at the end of a word or sentence. There it represents a glottal stop, an abrupt ending.

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  • Nice answer. Maybe you could add some examples, especially in your second paragraph. – Earthliŋ Jan 5 '17 at 8:51
  • I agree, some examples would be nice. You say, only unvoiced consonants can be geminated. Does this apply to Hiragana and Katakana? And what is with the Z- and Y-row? Does it double or not? – Pii83 Jan 5 '17 at 9:32
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    The ざ row is voiced, so won't geminate in any native words. Examples of gemination in semivowels like Y and W are extremely hard to find, at least for me. I would expect や to take い in the same way that わ takes う. – Fox Jan 5 '17 at 10:01
  • Thanks a lot. Finally it makes sense to me and I begin to understand what is meant by voiced and unvoiced. I think my question is answered by that. – Pii83 Jan 5 '17 at 10:29
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    P is unvoiced. This site elearnenglishlanguage.com/blog/learn-english/pronunciation/… is geared toward English-learning, but it has a nice description of what distinguishes voiced from unvoiced consonants. – Fox Jan 14 '17 at 4:31

For one thing, [v] is not a legitimate consonant in native Japanese. You may see it used in loanwords, but the pronunciation varies between speakers; some native speakers, especially younger generations, pronounce it as a [v], but some people still pronounce it as a [b], which is what has historically been used in Japanese to approximate a [v] sound. So it falls into the same category as [b].

For M, っ is not used; instead a ん is used preceding it; so "hammer" is written as ハンマー, not *ハッマー. This is also the case for N. As for W, there are no native words (that I'm aware of) that use a geminate [w] sound, and I actually can't think of a word in any language that would end up being transcribed in such a way that you would need to, but I suppose it wouldn't be incorrect to use a っ with it.

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The small つ (written as っ) is used to represent a very brief pause before the next consonant. These occur in the readings of Kanji and in hiragana grammatical conjugations. This is Romanised as a double consonant and used to represent them (with ッ) in foreign words. The reason that つ is used is that "tsu" sounds are often replaced with pauses in compound words. This is similar to the voicing of second Kanji in compound words (such as [川]{river} being read as かわ or がわ in different words).

For example, use in grammatical conjugations:


I bought the Apple


It was delicious


Please wait

Use in Kanji readings:




Sapporo (City)


Hokkaido (Island/Prefecture)

This pause is also used for sudden stops in conversational speech:





Since the sound following depends on the next Kanji, not they one preceding it, the っ could occur before any sound that occurs native in Japanese (including voiced consonants G, Z, J and yoon syllables). However, notice that Fa, Fi, Fe, C, V, and Wi do not occur natively in Japanese and are only used in foreign names (or very recent loanwords).

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    If this answer were accurate, you would be able to pronounce っ in あっさり or マッハ or ヘッド by "pausing", but you can't. – snailplane Jun 16 '18 at 12:13
  • Many textbooks (written by Native speakers) describe it as a pause (or the silent tsu). I’ve described it specifically in native Japanese words since foreign loanwords (where the usage differs) has been excellently described already. This is also why there are only “double consonants” and no other consonant diphthongs in Japanese. – Tom Kelly Jun 16 '18 at 12:17
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    あっさり is a native Japanese word, and yet you must extend the /s/ sound rather than pause if you want to pronounce it. It is hardly an exception; "pause" is incorrect as a description for gemination. By the way, a "diphthong" is a vowel sound which changes in quality from one place of articulation to another over time. Unfortunately, your last sentence doesn't appear to mean anything in particular. – snailplane Jun 16 '18 at 12:21
  • It’s a very difficult sound to describe. I’ve seen many textbooks attempt to do so in different ways but most call it a very short pause. Of course, there’s no substitute to being in Japan or talking to native speakers to learn correct pronunciation (romanising words can only go so far). I hope that putting it in context and giving some different examples helps some people. If you think you can describe it more accurately, please be my guest. Please try to do so in non-technical terms: not all Japanese learners are linguists. – Tom Kelly Jun 16 '18 at 12:30

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