Japanese Numbers and Counters: How to Count Anything

Japanese numbers are wonderfully logical — 11 is literally "ten-one" (じゅういち), 234 is "two-hundred three-ten four" — right up until they aren't. A handful of sound changes (300 is sanbyaku, not sanhyaku) and the counter system (you can't just say "three pencils" — you need sanbon) are where learners stumble. This guide covers the whole system, irregulars included.

1 to 10: the foundation

Note that 4, 7, and 9 each have two readings. In practice, よん, なな, きゅう dominate — partly because し and くsound like the words for death and suffering. Which reading appears depends on the word: 4 o'clock is よじ, April is しがつ, 9 o'clock is くじ. These have to be learned per word — typing practice handles that beautifully.

Building big numbers (and the sound changes)

Stack the units: 百 (100), 千 (1,000), 万 (10,000). Japanese groups by 10,000 — one million is 百万 (100 × 10,000), and 100,000,000 gets its own unit, 億. The catch is euphony — some combinations mutate:

Everything else is regular: 234 = にひゃくさんじゅうよん, 56,000 = ごまんろくせん. The mutations above are a closed list — drill them a few times and big numbers hold no surprises.

Counters: how Japanese counts things

Japanese numbers rarely stand alone — they take a counter wordthat matches what's being counted, like "three sheetsof paper" for everything. The big six cover most of daily life:

The pattern worth internalizing: counters starting with h/p/s/k mutate after 1, 3, 6, 8, and 10 — the same euphony as the hundreds. いっぽん (one bottle), さんぼん (three), ろっぽん (six). It feels chaotic for a week, then your mouth starts doing it automatically — the mutations exist precisely because they're easier to say.

Numbers in the wild: prices and phone numbers

Two everyday formats are worth special practice. Prices are just number + 円 (en): １２０円 is ひゃくにじゅうえん, and the mutations show up exactly where you'd expect — ８００円 is はっぴゃくえん, ３０００円 is さんぜんえん. Convenience store totals are a free daily quiz. Phone numbers go the other way: read digit by digit, with ぜろ (or まる) for 0, and 4 and 7 read よん and なな to avoid mishearing — 090 is ぜろきゅうぜろ. If you can rattle off your own phone number in Japanese, the digit readings are yours for life.

How to make all this automatic

Number readings are a recall skill — you hear a price, see a date, and need the reading instantly. Reading about さんびゃくwon't do it; producing it will. The free time & numbers course randomizes numbers, prices, and counters so every rep is a fresh retrieval: see ８００円, type happyakuen, next. Dates and times have their own irregular system — covered in days, dates, and months in Japanese.