# What Is Borderline Intellectual Functioning? IQ 70–84 and 1 in 7

> Borderline intellectual functioning is the name for an IQ of roughly 70 to 84 (between the under-70 benchmark for intellectual disability and the average range of 85 and above), and it is not a diagnosis. It corresponds to −2 SD to −1 SD on a normal distribution with a mean of 100 and an SD of 15, so in theory 13.59% of the population (about 1 in 7.4) falls in this band; "about 14%" is that figure rounded, not a measured value for Japan. DSM-5 places it not under intellectual developmental disorder but under "Other Conditions That May Be a Focus of Clinical Attention" (R41.83), while intellectual disability is judged on both intellectual functioning and impairment in daily life. The cutoffs are conventions, and because tests carry several points of error, a one-point difference does not change the meaning. The ryoiku techo disability certificate tends to be out of reach for this band, and the places to turn include Developmental Disabilities Support Centers.

- URL: https://brainrank.jp/en/blog/borderline-intelligence
- Published: 2026-09-17
- Publisher: BrainRank Editorial Team (https://brainrank.jp)
- Tags: IQ basics, Percentages

Borderline intellectual functioning is the name for an IQ of roughly 70 to 84, the band between the under-70 range used as the benchmark for intellectual disability and the 85-and-above range treated as average. It is not a disease or a diagnosis. On a normal distribution with a mean of 100 and a standard deviation (SD) of 15, it corresponds to −2 SD to −1 SD, so in theory 13.6% of the population, about 1 in 7, falls in this band. This article lays out the basis for the range and the percentage, how it differs from intellectual disability and developmental disorders, the ryoiku techo disability certificate, the effects on daily life and work, and where to seek help, drawing on official documents and research. Individual judgments belong with testing and consultation at a specialist institution.

## What IQ range counts as borderline intellectual functioning? Why 70 and 85 are the cutoffs

The cutoffs of 70 and 85 come from the basic rule behind [how IQ works](https://brainrank.jp/en/iq): a mean of 100 and an SD of 15. Two SDs below the mean is 70, and one SD below is 85. By convention in intelligence testing, 85 to 115 (the mean ±1 SD, 68.27% of the population) is the average range and below 70 (2.28%) is the benchmark for impaired intellectual functioning, so the band in between, 70 to 84, has come to be called borderline intellectual functioning.

Converted to a deviation score (mean 50, SD 10), IQ 70 is 30, IQ 84 is 39.3, and IQ 85 is 40; you can see where they sit on the distribution at [IQ 70](https://brainrank.jp/en/iq/70), [IQ 85](https://brainrank.jp/en/iq/85), and the [IQ distribution data](https://brainrank.jp/en/data/iq-distribution). The cutoffs do shift a little across sources, though: the definition through DSM-IV was 71 to 84, Japanese books and press use 70 to 84, the descriptive classification "Borderline" on the WAIS-IV and WISC-IV covers 70 to 79 (renamed "Very Low" in the WISC-V), and the Ministry of Health, Labour and Welfare's benchmark for intellectual disability is "roughly up to 70." The "Borderline" labels in BrainRank's reference table, results report, and distribution data are the site's own bands (70 to 79 in the reference table, under 80 in the results report, 55 to 70 in the distribution data) and cover a different range from borderline intellectual functioning (70 to 84).

## "About 1 in 7" is a theoretical figure from the normal distribution

"About 14%, or 1 in 7" is not a count measured in Japan; it is a value calculated on the normal-distribution model. On a normal distribution with a mean of 100 and an SD of 15, 15.87% falls below IQ 85 and 2.28% below IQ 70, so the difference, 15.87% − 2.28% = 13.59%, falls in the 70-to-84 band, and 1 ÷ 0.1359 ≈ 1 in 7.4. "About 14%" is that 13.6% rounded, and the "about 14% of the population" figure in the editor's note on the publisher's page for [Keki no Kirenai Hiko Shonen-tachi ("The Young Offenders Who Can't Cut a Cake," Shinchosha)](https://www.shinchosha.co.jp/book/610820/), one of the books that made the term widely known, is the same calculation.

Measured values vary by population and test. In a British birth cohort of 15,453 people, 2,108 (13.6%; that study defined the band as IQ 71 to 85) fell in this range ([Hassiotis and colleagues, 2019, BMC Psychiatry](https://pmc.ncbi.nlm.nih.gov/articles/PMC6896708/)). By contrast, a British general-population survey ([Hassiotis and colleagues, 2008, 8,450 adults](https://pubmed.ncbi.nlm.nih.gov/18197948/)) cited in the review by [Lee and Cheon (2024)](https://pmc.ncbi.nlm.nih.gov/articles/PMC11220481/) put the figure at 12.3%. How to read the average range (85 to 115) is covered in [Is an IQ of 90 low?](https://brainrank.jp/en/blog/iq-90-meaning).

## Borderline intellectual functioning is not a diagnosis: how it differs from intellectual disability and developmental disorders

Borderline intellectual functioning is not a medical diagnosis. In the American Psychiatric Association's DSM-5 it is not treated as a neurodevelopmental disorder such as intellectual developmental disorder (intellectual disability); it is listed as one item under "Other Conditions That May Be a Focus of Clinical Attention" (ICD-10-CM code R41.83) ([Hassiotis and colleagues, 2019](https://pmc.ncbi.nlm.nih.gov/articles/PMC6896708/)). DSM-5 also dropped the IQ range, and it has been pointed out that a clear definition no longer exists ([Wieland and Zitman, 2016, BJPsych Bulletin](https://pmc.ncbi.nlm.nih.gov/articles/PMC4967780/)).

Intellectual disability, by contrast, is not decided by IQ alone. Under the Ministry of Health, Labour and Welfare's definition, it is a state in which impaired intellectual functioning (an IQ of roughly up to 70) appears during the developmental period and daily life is affected enough to require special assistance ([MHLW, glossary for the Basic Survey on Children and Adults with Intellectual Disabilities](https://www.mhlw.go.jp/toukei/list/101-1c.html)). Developmental disorders are judged on yet another diagnostic axis and can co-occur with borderline intellectual functioning. The accurate framing is that it is neither a "developmental disorder gray zone" nor "a type of intellectual disability"; it is only a label for where an IQ sits.

So can a test tell you whether you have borderline intellectual functioning? Formal intelligence tests such as the WAIS (adults) and the WISC (children) are administered individually by trained professionals ([what is the WAIS?](https://brainrank.jp/en/blog/iq-tests-wais)), and the results report includes a 90% or 95% confidence interval that allows for measurement error. The cutoffs are conveniences, and given that error, a one-point difference like "I got 86 on the WAIS-IV" versus "I got 85" does not change the meaning. Around 85, the first step is not to interpret the composite score but to sit down with the examiner and read the gaps among the four indexes (Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed) against your actual difficulties. Online estimates, BrainRank's included, differ from formal tests in both question format and testing conditions, so they cannot be used to determine borderline intellectual functioning, and reference pages such as [IQ 85](https://brainrank.jp/en/iq/85) only show a position on the distribution.

## Can you get a ryoiku techo? Why the criteria differ by local government

The ryoiku techo disability certificate 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 operating rules, including the assessment criteria ([MHLW, "About disability certificates"](https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/hukushi_kaigo/shougaishahukushi/techou.html)). The underlying 1973 Ministry of Health and Welfare notice is technical advice, and all the national government defines is the benchmark for the severe grade (A), such as an IQ of roughly 35 or below accompanied by a need for care or behavioral problems, and a grade (B) for everything else ([MHLW, "Overview of the ryoiku techo system"](https://www.mhlw.go.jp/content/12200000/001679542.pdf)).

The upper IQ limit for eligibility is set by each local government's implementation guidelines. A secondary-source summary states that "in principle, a certificate cannot be issued when the IQ exceeds 76," though some local governments do issue one after weighing co-occurring conditions such as developmental disorders as a whole ([Wikipedia, "Ryoiku techo"](https://ja.wikipedia.org/wiki/療育手帳)). Many people with an IQ of 70 to 84 therefore tend to fall outside the system, and this is the institutional reason the band is called a "support gap." If a developmental disorder or a mental illness is also present, other routes such as the mental health and welfare certificate for persons with mental disorders may be available, so check with the disability welfare desk of the local government where you live.

## What does an IQ of 70 to 84 mean for daily life and work?

[Peltopuro and colleagues (2014, Intellectual and Developmental Disabilities)](https://pubmed.ncbi.nlm.nih.gov/25409130/), in a systematic review of 49 papers, concluded that people with borderline intellectual functioning are prone to neurocognitive, social, and mental health difficulties, and that adults are more likely than the general population to end up in low-skill, low-wage jobs, yet the group has received almost no attention as a subject of research, so support systems need to be built.

The British cohort mentioned above likewise reported that people in this band had a significantly higher risk of psychological distress in adulthood ([Hassiotis and colleagues, 2019](https://pmc.ncbi.nlm.nih.gov/articles/PMC6896708/)). These are group tendencies, though; an individual's difficulties come from the interaction between a trait (taking longer to understand things) and an environment that relies on verbal instructions, skips confirmation, and puts speed first. Haruhisa Ota of the Showa University Medical Institute of Developmental Disabilities has also objected to the trend of using the term as a label on social media, stating that "whether an IQ is high or low ... is not a measure of a person's humanity" ([PRESIDENT Online, 2024](https://president.jp/articles/-/78463)).

For the worry "I'm a new hire, I'm slow to understand things, and I can't learn the job," the realistic answer is environmental design, not willpower. What works is documenting procedures and building in checks: write verbal instructions down on the spot and repeat them back, turn work steps into a personal checklist, and schedule a midpoint check-in with your manager before the deadline. You can also ask the workplace for accommodations, such as receiving instructions in writing or being handed fewer tasks at once (with a diagnosis such as a developmental disorder, these may qualify as reasonable accommodations). Nor is the right job decided by IQ alone; as covered in [IQ and career](https://brainrank.jp/en/blog/iq-and-career), the sensible approach combines your strengths and weaknesses by domain with how easily that workplace can adjust the environment.

## Does IQ change? Does a childhood result carry into adulthood?

Questions like "I was told my IQ was 81 in elementary school" or "my IQ was 82 in junior high; is it the same as an adult?" can be answered from how IQ works. IQ expresses a relative position within a same-age group, so it does not rise automatically as you gain knowledge in adulthood ([IQ and age](https://brainrank.jp/en/blog/iq-and-age)). At the same time, [Ramsden and colleagues (2011, Nature)](https://pubmed.ncbi.nlm.nih.gov/22012265/) retested the same teenagers a few years later and reported that both verbal and nonverbal IQ went up in some people and down in others. The type of test, your condition on the day, and familiarity with the format also move the score by a few points, so values near a cutoff can change classification on retesting. A single childhood result is "the result of that test at that time": neither fixed for life nor something you automatically leave behind as an adult ([IQ tests for children](https://brainrank.jp/en/blog/children-iq-test)).

The questions "are there highly educated people with borderline intellectual functioning?" and "is effort pointless?" fit the same framework. [The correlation between IQ and academic performance is roughly 0.5](https://brainrank.jp/en/blog/iq-and-grades), so IQ explains only about a quarter of the variance in grades, with the rest coming from study time, teaching quality, and the home and school environment. At a correlation of 0.5, people in the borderline range who achieve academically are not statistically rare. No established method moves the IQ number itself by much ([can you raise your IQ?](https://brainrank.jp/en/blog/how-to-raise-iq)), but knowledge, skills, and mastery of procedures accumulate at any age, and what helps people stay employed is the environmental adjustment described above. The answer that fits the research is neither "effort is pointless" nor "effort solves everything," but arranging the environment so that effort pays off.

## Where to go for help

Which service to use depends on who is struggling and with what. For the general concerns of the individual or the family, the first stop is a Developmental Disabilities Support Center, which prefectures and designated cities establish or designate; it provides guidance and advice in coordination with related agencies ([National Rehabilitation Center for Persons with Disabilities, "What is a Developmental Disabilities Support Center?"](https://www.rehab.go.jp/ddis/action/about/)). If mental health is the main concern, the contact is a Mental Health and Welfare Center, which each prefecture and designated city operates under Article 6 of the Mental Health and Welfare Act ([National Council of Mental Health and Welfare Center Directors](https://www.zmhwc.jp/center.html)).

For children and parents, the contact is the education consultation center of the local board of education; the Tokyo Metropolitan Education Consultation Center, for example, takes inquiries by phone (0120-53-8288), in person, and by email ([Tokyo Metropolitan Education Consultation Center](https://e-sodan.metro.tokyo.lg.jp/)). Employment transition support is limited to "persons with disabilities under 65 who wish to work and are expected to be able to obtain employment at a regular workplace" ([MHLW, "Contents of disability welfare services"](https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/hukushi_kaigo/shougaishahukushi/service/naiyou.html)), so whether borderline intellectual functioning alone qualifies depends on the local government and the physician's judgment. Formal testing is available at medical institutions and also through education consultation or the support centers.

Finally, a line between what an online test can and cannot do. [BrainRank's free IQ test](https://brainrank.jp/en/start) 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 overall estimate plus your profile by domain. 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). It can help you see your strengths and weaknesses by domain, but it cannot determine whether you fall into borderline intellectual functioning, so do not draw that conclusion about yourself or your child from the numbers on a results page alone. Results are estimates for entertainment and self-understanding, not a medical or diagnostic assessment. If you are concerned, seek formal testing and consultation at the services listed above.

## Frequently asked questions

### How many people have borderline intellectual functioning?

On a normal distribution with a mean of 100 and a standard deviation of 15, 13.59% of people fall between IQ 70 and 84 (−2 SD to −1 SD), or about 1 in 7.4. That is the 15.87% below IQ 85 minus the 2.28% below IQ 70, and "about 14%" or "1 in 7" are roundings of this theoretical value. It is not a measured count for Japan, and the figure moves with the population and the test: a British birth cohort found 13.6% (that study defined the band as IQ 71 to 85), while a separate survey of 8,450 British adults found 12.3%.

### Is an IQ of 85 borderline? I scored 86 on the WAIS-IV.

By convention, IQ 85 and above counts as the average range, so 85 or 86 falls outside borderline intellectual functioning. But the cutoffs of 70 and 85 are statistical conventions, and even formal intelligence tests carry several points of measurement error, with results reported alongside a confidence interval, so a one-point difference does not change the meaning. Rather than focusing on the composite IQ number, it is more practical to go over the results with the examiner and check whether the strengths and weaknesses across the indexes match your day-to-day difficulties.

### Can you get a ryoiku techo with borderline intellectual functioning?

The ryoiku techo disability certificate is issued to people judged to have an intellectual disability by a child guidance center or an intellectual disability rehabilitation consultation office, and the criteria are set by each local government's implementation guidelines. The national notice defines only the benchmark for the severe grade (A), and the upper IQ limit for eligibility varies by local government, but a secondary-source summary states that "in principle, a certificate cannot be issued when the IQ exceeds 76," so in practice many people with an IQ of 70 to 84 tend to fall outside it. If a developmental disorder or a mental illness is also present, other routes such as the mental health and welfare certificate for persons with mental disorders may be available, so check with the disability welfare desk where you live.

## Sources

- [Keki no Kirenai Hiko Shonen-tachi ("The Young Offenders Who Can't Cut a Cake," Shinchosha)](https://www.shinchosha.co.jp/book/610820/)
- [Hassiotis and colleagues, 2019, BMC Psychiatry](https://pmc.ncbi.nlm.nih.gov/articles/PMC6896708/)
- [Hassiotis and colleagues, 2008, 8,450 adults](https://pubmed.ncbi.nlm.nih.gov/18197948/)
- [Lee and Cheon (2024)](https://pmc.ncbi.nlm.nih.gov/articles/PMC11220481/)
- [Wieland and Zitman, 2016, BJPsych Bulletin](https://pmc.ncbi.nlm.nih.gov/articles/PMC4967780/)
- [MHLW, glossary for the Basic Survey on Children and Adults with Intellectual Disabilities](https://www.mhlw.go.jp/toukei/list/101-1c.html)
- [MHLW, "About disability certificates"](https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/hukushi_kaigo/shougaishahukushi/techou.html)
- [MHLW, "Overview of the ryoiku techo system"](https://www.mhlw.go.jp/content/12200000/001679542.pdf)
- [Wikipedia, "Ryoiku techo"](https://ja.wikipedia.org/wiki/療育手帳)
- [Peltopuro and colleagues (2014, Intellectual and Developmental Disabilities)](https://pubmed.ncbi.nlm.nih.gov/25409130/)
- [PRESIDENT Online, 2024](https://president.jp/articles/-/78463)
- [Ramsden and colleagues (2011, Nature)](https://pubmed.ncbi.nlm.nih.gov/22012265/)
- [National Rehabilitation Center for Persons with Disabilities, "What is a Developmental Disabilities Support Center?"](https://www.rehab.go.jp/ddis/action/about/)
- [National Council of Mental Health and Welfare Center Directors](https://www.zmhwc.jp/center.html)
- [Tokyo Metropolitan Education Consultation Center](https://e-sodan.metro.tokyo.lg.jp/)
- [MHLW, "Contents of disability welfare services"](https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/hukushi_kaigo/shougaishahukushi/service/naiyou.html)

---

Statistics and percentages are calculated from a normal distribution model with a mean of 100 and a standard deviation of 15. The tests on this site provide estimates for entertainment and self-understanding; they are not medical or clinical assessments, nor official intelligence tests.
When citing, credit "BrainRank (brainrank.jp)" and link the article URL.