Lesson 27 — Counter Suffixes and Their Pronunciation

What Is a Counter Suffix?

In Japanese, you can’t count things with numbers alone. You must attach a counter suffix (助数詞 じょすうし) — a small word placed directly after the number that indicates what kind of thing is being counted.

For example, to count the floors of a building, you use the counter 階（かい）:

1階、2階、3階、4階…

This is straightforward when reading silently. But saying it aloud reveals a challenge — the actual pronunciations are:

いっかい、にかい、さんがい、よんかい

This raises several questions:

• Why does 1 become いっ in いっかい, but stay いち in 1年（いちねん）?
• Why does the counter become voiced in 3階（さんがい）and 3千（さんぜん）, but not in 3回（さんかい）or 3線（さんせん）?

This lesson explains the patterns — and the exceptions — behind these sound changes.

💡 Why do these changes happen at all? Almost every sound change in Japanese counters exists for one reason: ease of pronunciation. Certain number-plus-counter combinations are awkward to say quickly, so the sounds shift to flow more smoothly. Understanding this principle makes the patterns far less arbitrary.