How rare is an IQ of 70?
An IQ of 70 is at the Borderline range. Under a normal model with mean 100 and standard deviation 15, IQ 70 or above has the following estimated frequency.
Deviation score
30
Top
97.72%
Rarity
1 in 1
z-score
-2
On the normal-distribution model with a mean of 100 and a standard deviation of 15, an IQ of 70 corresponds to roughly the top 97.72% (about 1 in 1 people), a deviation score of 30, and a standard score of z = -2. All four values are computed from that model rather than aggregated from test-taker data; the calculation is documented on our methodology page.
Position in the IQ distribution (mean 100, SD 15)
How the percentages are calculated
We assume a normal distribution with mean 100 and SD 15. Φ is the standard normal cumulative distribution function. Values are rounded for display.
- Standard score
- z = (70 − 100) ÷ 15 ≈ -2
- Share scoring 70 or above
- [1 − Φ((70 − 100) ÷ 15)] × 100 ≈ 97.72%
- Deviation score
- 50 + (70 − 100) ÷ 15 × 10 ≈ 30
NIST: Normal Distribution documents the distribution and its cumulative function. The mean-100, SD-15 assumption is the model used on this page, not evidence that an online test is standardized.
These frequencies describe scores at or above the stated IQ, not the number with exactly that score. Confidence intervals depend on the test and its reliability; BrainRank has not established a validated ±5-point interval.
Does 5 points matter? IQ 65 / 70 / 75 compared
| IQ | Top % | Rarity |
|---|---|---|
| IQ65 | 99.02% | 1 in 1 |
| IQ70this page | 97.72% | 1 in 1 |
| IQ75 | 95.22% | 1 in 1 |
This table compares theoretical population shares. It does not establish whether a five-point difference between two test results is meaningful; that depends on the test and its reliability.
How to interpret an IQ of 70
Use the number to understand a position on a scale, then check what the particular test measures.
- •On the mean-100, SD-15 model, IQ 70 is 30 points below the mean; the share scoring 70 or above is about 97.72%.
- •A single IQ number does not identify which tasks you find easy. Read it alongside the test's scope and your scores in each area.
- •Compare scores only after checking the test, reference group, and standard deviation. A BrainRank estimate is not interchangeable with a standardized assessment.
Relationship to Mensa
Mensa requires a score in the top 2% on an approved, properly administered and supervised intelligence test. Under the mean-100, SD-15 normal model, IQ 70 or above corresponds to the top 97.72%. Admission cutoffs depend on the accepted test; a BrainRank estimate or certificate cannot establish eligibility.
Source: Mensa International — IQ Test FAQs
Note: Most celebrity IQ figures seen online are estimates from unreliable sources. This page does not publish individual IQ values that cannot be verified.
Frequently asked questions
- What percentile is an IQ of 70?
- An IQ of 70 corresponds to roughly the top 97.72%, or about 1 in 1 people scoring 70 or above, assuming a normal model with mean 100 and SD 15.
- Is an IQ of 70 high? Is it impressive?
- It is at the Borderline range, placing it in roughly the top 97.72%. That said, IQ measures only a small part of thinking and does not determine a person's worth or success.
- Can you join Mensa with an IQ of 70?
- Mensa requires a score in the top 2% on an approved, properly administered and supervised intelligence test. Under the mean-100, SD-15 normal model, IQ 70 or above corresponds to the top 97.72%. Admission cutoffs depend on the accepted test; a BrainRank estimate or certificate cannot establish eligibility.
- What is the deviation score for an IQ of 70?
- Converting IQ (mean 100, SD 15) to a deviation score gives about 30.
Common questions in the IQ 70–79 band
- Does an IQ of 70 mean something is wrong?
- No single unsupervised online score can answer that. An IQ around 70 on an informal test is only a rough estimate, and formal assessment always combines a supervised test with an evaluation of daily functioning by a qualified professional. If you have concerns, consult a specialist rather than relying on one number.
- Can a score around 70 go up if I retake the test?
- Yes, it can. Fatigue, unfamiliarity with the question format, and concentration on the day all push scores down. With rest and some familiarity with puzzle-style items, retest scores in this range often move by several points in either direction.
- Should I compare an informal score of 70 to clinical cutoffs?
- No. Clinical categories are defined for standardized, supervised tests administered by professionals. An informal online estimate of 70 is not a diagnosis and should not be mapped onto clinical labels.
Age and testing conditions
- •IQ is a deviation score relative to people of the same age: a score compares you with your own age group, so children's and adults' scores are not on the same footing.
- •Results from informal online tests, including the test on this site, are estimates. For medical or educational decisions, use a standardized test administered by a qualified professional.
- •Sleep deprivation, fatigue, and practice effects all move measured scores. Read any single result, high or low, with that in mind.