Is an IQ of 70 good or bad?
An IQ of 70 is low: two standard deviations below the average of 100, higher than about 2.3% of people, or roughly 1 in 44 at or below. It is the traditional reference point for intellectual disability, but it is not a hard cut-off, and "good" or "bad" are the wrong words for any score.
How far below average is 70?
An IQ of 70 is 30 points below the average of 100, or 2 standard deviations. About 2.3% of people of the same age score lower, the shaded sliver at the far left of the curve below.
On a test with a standard deviation of 16, such as older Stanford-Binet editions, the same result would be about 68, and on the Cattell scale, which uses 24, about 52. Why scales differ.
What an IQ of 70 tells you
70 is the mirror of 130. Both are two standard deviations from the middle, and both are reached by about 1 person in 44: one is the usual Mensa line, the other the usual reference point for an intellectual disability. The American Psychiatric Association says intellectual disability is "approximately two standard deviations or more below the population, which equals an IQ score of about 70 or below".
The word "about" matters. In Hall v. Florida (2014), the Supreme Court struck down a Florida rule that treated 70 as a strict cut-off, because tests have a standard error of measurement and a score of 71 or 72 can reflect the same ability. On the Assessivo test, 70 means six correct answers out of 36, a result pure guessing falls to about one time in six.
How an IQ of 70 is classified
Different tests and manuals use different words for the same score, and the words have changed over time. Here is where 70 falls on each of the systems you are most likely to meet.
Sources: American Psychiatric Association, DSM-5 fact sheet on intellectual disability; World Health Organization, ICD-11, 6A00 disorders of intellectual development; Peltopuro, M. and others (2014), "Borderline intellectual functioning: a systematic literature review", Intellectual and Developmental Disabilities, 52(6), 419–443. WISC-V descriptors from Pearson's interpretive reports, as on our good IQ score guide.
Does 70 mean an intellectual disability?
A score of 70 on its own never makes a diagnosis. The American Psychiatric Association's DSM-5 describes intellectual disability as "approximately two standard deviations or more below the population, which equals an IQ score of about 70 or below", and requires three things together:
- Low intellectual functioning, confirmed by a clinical assessment and individually given, standardised testing.
- Difficulties with everyday adaptive skills in at least one of three domains: conceptual (language, reading, maths, memory), social (communication, judgement, friendships) and practical (personal care, money, work and school tasks).
- A start during the developmental period, in childhood or adolescence.
Severity is set by those everyday skills, not by the IQ number. That is why only about 1% of people have an intellectual disability (a 2011 meta-analysis of 52 population studies found about 10 per 1,000), even though about 2.3% score below 70 on the bell curve. Because tests have a margin of error, DSM-5 treats roughly 65 to 75 as the uncertain zone around 70.
Sources: American Psychiatric Association, DSM-5 fact sheet on intellectual disability; Maulik, P. K. and others (2011), "Prevalence of intellectual disability: a meta-analysis of population-based studies", Research in Developmental Disabilities, 32(2), 419–436; Hall v. Florida, 572 U.S. 701 (2014), which cites the DSM-5 range of 65 to 75.
Borderline intellectual functioning and an IQ of 70
Scores from roughly 70 to 85 are often described as borderline intellectual functioning. It is not a diagnosis of intellectual disability: most people in this range live independently, work and raise families. But a 2014 systematic review of 49 studies found that the group faces more neurocognitive, social and mental health difficulties than average, and called it "almost invisible" in research and services.
On a perfect bell curve, about 13.6% of people score between 70 and 85, so this is far from rare. People in the range often learn best with clear, concrete instructions, worked examples and extra time for new or written tasks, and often do well in practical, hands-on work.
Source: Peltopuro, M. and others (2014), "Borderline intellectual functioning: a systematic literature review", Intellectual and Developmental Disabilities, 52(6), 419–443.
Why scores near 70 matter in US courts
In Atkins v. Virginia (2002), the US Supreme Court ruled that executing a person with an intellectual disability is unconstitutional, and left states to decide who qualifies. In Hall v. Florida (2014) it struck down a rule that treated 70 as a strict cut-off, because every test has a margin of error. In Moore v. Texas (2017) it said courts must be guided by current medical standards rather than "lay stereotypes".
The practical lesson is the same outside a courtroom: a score of 70 is best read as a range, about 65 to 75, and judged alongside how a person actually manages daily life.
Sources: Atkins v. Virginia, 536 U.S. 304 (2002); Hall v. Florida, 572 U.S. 701 (2014); Moore v. Texas, 581 U.S. 1 (2017).
Is your 70 accurate?
Low scores are the most fragile results on any test, because almost everything that goes wrong on the day pulls a score down. Common reasons include:
- Running out of time. On timed tests, including ours, an unanswered question counts as wrong.
- Nerves. A review of 238 studies found test anxiety consistently linked with lower scores.
- Tiredness. Sleep loss hits attention and speed hardest, which costs points against the clock.
- Language and format. Taking a test in a second language, on a small screen or in an unfamiliar format can lower a result without saying anything about reasoning.
What a 70 means on our test
On the Assessivo test, 70 means 6 correct answers out of 36. Every question has four options, so someone guessing every answer at random averages nine correct, a score of 78. Random guessing falls this low about once in 6 attempts, so it can happen by bad luck, but it more often means many questions were skipped or rushed.
If any of this sounds like your session, retake the free IQ test when you are rested and have 25 quiet minutes. A score that moves a lot between attempts was never very solid.
Sources: von der Embse, N. and others (2018), "Test anxiety effects, predictors, and correlates: a 30-year meta-analytic review", Journal of Affective Disorders, 227, 483–493; Lim, J. and Dinges, D. F. (2010), "A meta-analysis of the impact of short-term sleep deprivation on cognitive variables", Psychological Bulletin, 136(3), 375–389. Guessing figures are worked out from the binomial distribution for 36 four-option questions.
What is the mental age for an IQ of 70?
The first IQ tests, for children, described performance as a "mental age": the age whose typical performance a child matched. IQ was mental age divided by real age, times 100. Run that old formula backwards and you get the figures below, for children only.
| Child's age | Performs like a typical child of about |
|---|---|
| 6 | 4 years 2 months |
| 8 | 5 years 7 months |
| 10 | 7 years |
| 12 | 8 years 5 months |
| 14 | 9 years 10 months |
For adults the idea doesn't work, which is why David Wechsler replaced it in 1939 with today's method: compare each person with others of the same age. An adult who scores 70 has an adult's knowledge, interests and experience. The score only says how their test performance compares with other adults'.
How common is an IQ of 70?
Line up 100 people of the same age and about 2 would score 70 or lower; the orange dot marks the place. In a city of a million, about 22,800 people would be at or below this level.
The bar shows the likely range on a professional test, about five points either way: 65 to 75, from the 0.98th to the 5th percentile.
How 70 compares with nearby scores
| IQ | Percentile | Classic label | Score this low or lower |
|---|---|---|---|
| 60 | 0.38th | Extremely low | 1 in 261 |
| 65 | 0.98th | Extremely low | 1 in 102 |
| 70 | 2nd | Borderline | 1 in 44 |
| 75 | 5th | Borderline | 1 in 21 |
| 80 | 9th | Low average | 1 in 11 |
Questions about an IQ of 70
What percentile is an IQ of 70?
An IQ of 70 is at about the 2nd percentile: it is higher than about 2.3% of people of the same age, and roughly 1 person in 44 scores this low or lower.
Is 70 a low IQ?
Yes. 70 is 30 points, or 2 standard deviations, below the average of 100. On the classic Wechsler labels it is borderline, and the current children's Wechsler test calls it very low. A single score is an estimate with a margin of error of about five points, so 70 is best read as roughly 65 to 75.
Does an IQ of 70 mean intellectual disability?
Not on its own. 70 is in the range where an intellectual disability (called a learning disability in the UK) is considered, but a diagnosis also needs significant difficulties with everyday skills that began during childhood, assessed by a qualified psychologist.
What is the mental age for an IQ of 70?
Mental age is an idea from the earliest tests for children. By the old formula, a 10-year-old scoring 70 would perform like a typical child of about 7 years. For adults it has no meaning: modern IQ tests compare adults with other adults, and an adult who scores 70 is not like a child.
Is 70 IQ considered intellectually disabled?
Not automatically. About 70 or below is the usual reference range, but a diagnosis also needs significant difficulties with everyday skills that began in childhood. Because of measurement error, clinicians and courts treat scores from about 65 to 75 as a range, not a line.
Related: the IQ range chart, what counts as an average IQ, what IQ measures and misses and how to tell if an online IQ test is accurate.
Behind a single score of 70 sit several separate abilities. Read about fluid vs crystallized intelligence, abstract reasoning, spatial reasoning, verbal reasoning and processing speed, or try the free pattern recognition test.
Information and support
If a professional assessment has given you, your child or someone you care for a score like 70, these organisations explain what it means in practice and what help is available.
Want a second reading?
Take the free Assessivo IQ test when you are rested and have 25 quiet minutes: 36 questions, and your estimated score and percentile as soon as you finish.
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