Japanese Numbers

Definition:

Japanese has two parallel number systems that are both in active use: the Sino-Japanese system (borrowed from Chinese: ichi, ni, san…) and the native Japanese (Yamato) system (hitotsu, futatsu, mittsu…). Which system is used depends on the context and what counter is being used. Mastering both systems and their interaction with counters is one of the first major milestones in Japanese acquisition.

The Two Number Systems

Sino-Japanese Numbers (漢語数詞, kango-sūji)

These are derived from Chinese and are by far the most commonly used system:

Building Larger Sino-Japanese Numbers

Key difference from English: Japanese groups large numbers in units of 10,000 (万, man), not 1,000:

• 10,000 = ichiman (一万)
• 100,000 = jūman (十万), not one-hundred-thousand
• 1,000,000 = hyakuman (百万), literally “one hundred ten-thousands”

This causes difficulty for English speakers who think in thousands.

Native Japanese Numbers (和語数詞, wago-sūji)

When to use native Japanese numbers:

• When no specific counter is used (counting general items 1–9)
• When discussing someone’s age 1–10 in very casual contexts (less common today)
• Hitotsu, futatsu are used as a generic counter when no specialized counter applies

When to use Sino-Japanese:

• With specific counters (-hon, -mai, -hai, -hiki, etc.)
• For phone numbers, prices, dates, times, floors
• For numbers above 10 (native system only goes to 10 cleanly)

Counters and Number System Interaction

Different counters trigger different sound changes and may use different base numbers. This is explored fully in the Counters entry, but key examples:

Numbers in Context: Common Uses

Time:

• Hours: ichi-ji (1 o’clock), ni-ji (2 o’clock)
• Minutes: ippun (1 min), nifun (2 min), sanpun (3 min, sound change)

Dates:

• Days of month use a special archaic system for 1–10:
  tsuitachi (1st), futsuka (2nd), mikka (3rd), yokka (4th), itsuka (5th)
  From 11th onward: jūichinichi, etc.
  hatsuka (20th) — special form!

Money:

Prices always use Sino-Japanese: sen-en (₩1000), gosen-en (₩5000), ichiman-en (₩10,000).

Phone numbers / IDs:

Digits are read individually in Sino-Japanese: zero-san-ichi-no-go-roku-nana-hachi (031-5678).

Floors:

• 1F = ikkai (一階)
• 2F = nikai (二階)
• 4F = yonkai (avoid shikai due to death association)
• 8F = hachikai NOT hachikkai… though hakkkai also OK — irregular!

The 4 and 7 and 9 Dilemma

4 (四): Both shi and yon exist. Shi is avoided in some contexts because it’s homophonous with 死 (death). In counters: yonhon (4 long objects), yonmai, etc. — yon is standard. But 4th floor = yonkai, not shikai.

7 (七): Both shichi and nana. Nana preferred in phone numbers and counting to avoid confusion with ichi (1).

9 (九): Both ku and kyū. Ku can suggest 苦 (suffering/pain), so kyū is often preferred. Room 9 = kyūgōshitsu.

SLA Perspective

Japanese number acquisition typically proceeds:

1. Sino-Japanese 1–10 — very early (N5)
2. Combining for 11–100 — early N5
3. Tens, hundreds — N5
4. Thousands and ten-thousands, including the 万-grouping — N4
5. Complex sound changes with counters — protracted, even for advanced learners

The 万-grouping (vs. English thousand-grouping) causes persistent errors in L2 speakers of Japanese even at advanced levels, because it requires reformatting numbers mentally.

History

Japanese number vocabulary reflects historical layers of language contact: the native Japanese (Yamato) number series (hitotsu, futatsu, mittsu… kokonotsu, tō) is used for counting general objects up to 10 in isolation; the Sino-Japanese (on’yomi) number series (ichi, ni, san… ku/kyū, jū) was imported from Chinese literacy and became the basis for large number expressions, mathematics, time (hours using ji), dates, and most counter-noun constructions. Both systems have been in coexistence since the Nara period (8th century CE). The Sino-Japanese system’s dominance for most quantitative contexts reflects the prestige and functional utility of Chinese-derived vocabulary in formal Japanese registers, while the native series retains use in traditional counting, some traditional expressions, and specific counter combinations.

Common Misconceptions

“Japanese has only one number system.” Japanese has two parallel number systems — the native Japanese (hitotsu/futatsu series) and the Sino-Japanese (ichi/ni series). Both are used in modern Japanese with different distributions: the Sino-Japanese system dominates for most counting, mathematics, dates, and counter constructions; the native series is used for some objects when counting to 10, in traditional contexts, and with some specific counters. Learners need both systems, though the Sino-Japanese system has broader and more regular application.

“Large numbers in Japanese follow the same grouping as English.” Japanese groups large numbers in units of 4 (万 man = 10,000; 億 oku = 100,000,000; 兆 chō = 1,000,000,000,000) rather than English’s units of 3 (thousand, million, billion). This systematic difference means 100 million in English is 1億 (one oku) in Japanese — and conversions between English and Japanese large number expressions require restructuring the grouping, not just reading digits.

Criticisms

Number instruction in Japanese pedagogy has been criticized for insufficient emphasis on the systematic difficulty of large numbers — the 4-unit grouping difference is mentioned in most textbooks but typically in passing, without the sustained practice needed to build automatic conversion at the speed required for real-time comprehension. The dual-system structure is often poorly sequenced in introductory courses, creating early confusion about when to use which system. The JLPT’s N5-level number vocabulary focuses primarily on the Sino-Japanese system, which is pedagogically appropriate but may underemphasize the native counting series.

Social Media Sentiment

Japanese numbers and the large-number grouping difference are standard discussion topics in Japanese learning communities — the 万/億 vs. thousand/million mismatch is a perennially surprising discovery for English-speaking learners. Community members share the mnemonic and systematic approaches they use to convert large numbers quickly. Date reading (the Japanese year system gengō: Reiwa, Heisei, Shōwa years) is a related topic of community interest. The dual number system (native vs. Sino-Japanese) is initially confusing but commonly discussed as manageable once both systems are studied systematically.

Last updated: 2026-04

Practical Application

Learn the Sino-Japanese number series (ichi, ni, san, shi/yon…) first, as it covers most regular counting and counter constructions. Learn the native series (hitotsu, futatsu…) in parallel as it’s required for general object counting and culturally embedded expressions. Practice reading years, prices, and large quantities specifically in Japanese groupings — create focused exercises that require converting between English and Japanese large-number expressions (1 million dollars = 100万円). Sakubo presents Japanese number vocabulary in contextual sentences — building recognition of both number systems and their counter combinations through naturalistic vocabulary exposure.

Related Terms

• Counters — number classifiers that work with the number system
• JLPT N5 — level at which number basics are tested
• Japanese Particles — grammatical markers used alongside numbers
• Vocabulary Acquisition — how numbers fit into overall vocabulary learning

See Also

• Japanese Counters
• Japanese Grammar
• Kanji

Research

Shibatani, M. (1990). The Languages of Japan. Cambridge University Press.

A comprehensive linguistic description of Japanese including the numeral systems and their historical and grammatical distribution — the primary English-language reference for understanding the dual number system and its use in modern Japanese.

Miura, A. (1998). Japanese Numbers and Counting. Tuttle.

A focused reference for Japanese counting systems, number expressions, and the application of Sino-Japanese and native number series across different contexts — practical guidance for the learner navigating both counting systems.

Sato, H. (2004). Japanese Numeral Classifiers (Doctoral dissertation).

Research on Japanese numeral classification including the interaction between number forms and counter selection — relevant for understanding how number vocabulary integrates with the counter system in Japanese quantification.