Tanaka-Binet Intelligence Scale: IQ Scoring, V vs. VI, and WISC

The Tanaka-Binet Intelligence Scale is a Japanese individual intelligence test that Kan'ichi Tanaka created in 1947 based on the test devised by France's Alfred Binet; it is given one-on-one with an examiner and can be taken from age 2 through adulthood. On the widely used Tanaka-Binet Intelligence Scale V (published 2003), IQ through age 13 is derived from a mental age, which shows "up to what age level the child can solve items," and from age 14 it gives a deviation IQ for each domain. This article lays out how the IQ is calculated, how the V differs from the VI released in 2024, how the test is used for the ryoiku techo (Japan's disability certificate for intellectual disability), how it differs from the WISC, and where you can take it and what it costs, based on materials from the publisher and Japan's Ministry of Health, Labour and Welfare.

What is the Tanaka-Binet? Japan's individual test for ages 2 to adult

Binet-type intelligence tests go back to the test that Binet and Simon built in France in 1905. The Tanaka-Binet is its Japanese version: after Kan'ichi Tanaka's 1947 Tanaka Binet-shiki Chino Kensaho (Tanaka Binet-Type Intelligence Test Method), it was revised in 1954, 1970, and 1987. The 2003 Tanaka-Binet Intelligence Scale V was the fifth revision, the first in 17 years, and was standardized on 987 people between May and December 2001 (Ohkawa and colleagues, 2003, Ritsumeikan Journal of Human Sciences). In 2024 the publisher, Taken Shuppan, released the sixth edition, the Tanaka-Binet Intelligence Scale VI.

The test consists of items grouped by age level, from the 1-year level to the 13-year level, plus adult-level items. Each age level contains items that 60 to 70% of children that age pass (Ohkawa and colleagues, 2003). For children who cannot yet solve the 1-year-level items, there is a "developmental check" meant as a reference for care, and the publisher states that it is not to be treated as a diagnosis (Taken Shuppan). How the Binet and Wechsler approaches differ is covered in the history of the IQ test and What is the WAIS?.

How the IQ is calculated: mental age and ratio IQ through 13, deviation IQ from 14

For ages 2 to 13, the Tanaka-Binet V gives an intelligence quotient (IQ) and a mental age (MA); from age 14 it in principle gives a deviation IQ (DIQ) and no mental age (Ohkawa and colleagues, 2003). The IQ through age 13 is called a ratio IQ, and as a City of Yokohama appeal ruling puts it, it is found by dividing mental age by chronological age and multiplying by 100 (City of Yokohama).

• Chronological age 6 years 0 months and mental age 7 years 0 months: 7 ÷ 6 × 100 gives a ratio IQ of about 117
• Chronological age 8 years 0 months and mental age 6 years 0 months: 6 ÷ 8 × 100 gives a ratio IQ of 75
• When mental age equals chronological age, the ratio IQ is exactly 100

A ratio IQ intuitively shows how many years ahead of or behind their actual age a child is, but the same IQ does not necessarily mean the same position on the distribution (how rare it is) at different ages. That is why, from age 14, the test switches to a deviation IQ, which expresses position within a same-age group. From 14, it gives domain DIQs for four areas, crystallized, fluid, memory, and logical reasoning, plus an overall DIQ (Taken Shuppan). The idea behind deviation IQ is explained in What is IQ?, and the difference between crystallized and fluid intelligence in fluid and crystallized intelligence.

V vs. VI: the sixth edition arrived in 2024

In July 2024, Taken Shuppan announced the publication of the Tanaka-Binet Intelligence Scale VI, describing it as the sixth edition (Taken Shuppan). The biggest change in the VI is how results are expressed: for ages 2 years 0 months to 13 years 11 months, the main indicators are now mental age and a deviation IQ (DIQ), and from age 14 it gives domain DIQs and an overall DIQ. Where an administrative measure requires an adult ratio IQ, the publisher advises using the previous edition, the V (Taken Shuppan).

The other difference is insurance coverage. According to the publisher, the VI is not included in the national medical fee schedule, and it was not added in the fiscal 2026 revision either (Taken Shuppan, July 2026). Because the V and VI will be used side by side for the time being, you can avoid misreading results by checking which edition was used and, for children 13 and under, whether the figure is a ratio IQ or a deviation IQ.

The test most often used for ryoiku techo assessments

The ryoiku techo is issued to people judged to have an intellectual disability by a child guidance center or an intellectual disability rehabilitation consultation office, and each local government sets its own criteria. In a Ministry of Health, Labour and Welfare survey for fiscal 2024, 61.3% of assessment agencies named the Tanaka-Binet Intelligence Scale as the test they use most often, the highest share of any test (MHLW). It can be given from age 2, and its 1-year-level items and developmental check reach down to the earliest stages of development, which is why it is used to assess young children.

The national benchmark for the severe grade (A) includes "an IQ of roughly 35 or below," and the upper IQ limit agencies use for issuing a certificate is split, with 52% using "roughly IQ 75" and 27% "roughly IQ 70" (Children and Families Agency, 2024). Yokohama, for example, uses the Tanaka-Binet Intelligence Scale V and defines severe (A2) as an IQ of roughly 21 to 35 and moderate (B1) as 36 to 50 (City of Yokohama). How IQs of 70 to 84 are treated is covered in detail in What is borderline intellectual functioning?.

How it differs from the WISC: age range, how results are reported, and how scores come out

The other intelligence test commonly given to children is the WISC. The latest version, the WISC-V, covers ages 5 years 0 months to 16 years 11 months and gives a full-scale IQ plus five primary indexes (verbal comprehension, visual spatial, fluid reasoning, working memory, and processing speed); administering the subtests needed for the full-scale IQ takes about 45 to 60 minutes (Nihon Bunka Kagakusha). The Tanaka-Binet can be used from age 2 and expresses overall developmental level in terms of age, while the WISC is better suited to comparing strengths and weaknesses across domains (an uneven profile).

The two tests' numbers cannot be compared as they are. In the developers' data on 97 children aged 5 to 6, the mean IQ was 129.9 on the Tanaka-Binet V and the mean full-scale IQ was 115.6 on the WISC-III (correlation 0.693) (Ohkawa and colleagues, 2003). A separate study of 15 children likewise found 88.9 on the Tanaka-Binet V and 78.6 on the WISC-III, with the Tanaka-Binet V significantly higher (Proceedings of the Annual Convention of the Japanese Association of Educational Psychology, 2010). A gap like "90 on the Tanaka-Binet before, 80 on the WISC this time" does not necessarily mean ability has declined. How to read a WISC results report is covered in how to read WISC results, and children's testing in general in IQ tests for children.

Where can you take it? Cost and what to know beforehand

For a ryoiku techo assessment, the contact is a child guidance center for people under 18 and an intellectual disability rehabilitation consultation office for those 18 and older. At a medical institution, the test may be covered by national health insurance: in the medical fee schedule (effective June 2026), the Tanaka-Binet Intelligence Scale V is classified as a "complex procedure" worth 280 points and the WISC-V as an "extremely complex procedure and processing" worth 450 points (MHLW). At ¥10 per point, the standard 30% copay comes to ¥840 for the Tanaka-Binet V and ¥1,350 for the WISC-V for the test itself (consultation fees are separate).

The publisher does not state how long the test takes, but in the fee schedule it falls in the category of tests that require "roughly one hour or more for testing and processing results." Repeating the same test at short intervals tends to raise scores through familiarity with the items, so discuss the timing of any retest with the testing institution. It is important to have the results explained not just as a number but together with the examiner's observations, such as which items at which age level the child struggled with.

An online IQ test is no substitute for an individually administered test like the Tanaka-Binet. BrainRank's free IQ test is meant for adults and teenagers who want a rough sense of their own reasoning ability: it scores 20 questions (about 10 minutes) across four domains, spatial reasoning, pattern recognition, logical reasoning, and classification, using item response theory (IRT), and returns an estimate based on the deviation-IQ approach with a mean of 100 and an SD of 15. Parents who want to see the difference between ratio IQ and deviation IQ in their own results can use it too. Taking it is free with no signup; viewing the results, including the estimated IQ, is a one-time payment of ¥300 (tax included), with no subscription or auto-renewal (the result can be reopened for 24 hours after it is first shown, and saved as an image or PDF during that window). Results are estimates for entertainment and self-understanding and cannot be used for ryoiku techo assessments or for medical or diagnostic purposes.