UNDERSTANDING IQ SCORES

Is 121 a good
IQ score?

Yes. It is a high score. On the standard IQ scale, 121 is at roughly the 92nd percentile, about 1 in 12 at or above.

An IQ of 121 sits in the high range, higher than about 91.92% of people on a mean-100, SD-15 scale. This is a theoretical model comparison, not an observed population ranking. Here is what that means, and what it does not.

Reference score: 121
Percentile: 91.92%
At or above: 1 in 12
Reference scale: 100 mean / 15 SD

Prepared by IQInsight · Calculation guide · Updated 1 November 2026

121 sits just inside the band many manuals call superior.

A score of 121 is 1.4 standard deviations above the mean. The normal model places about 91.92% of values below it and 8.08% at or above it, around one in twelve. On WAIS-IV classifications, 120 to 129 is labelled superior; newer manuals such as the WISC-V call the same band very high.

Compared with 120, which is higher than about 90.88% of values, 121 is roughly one percentile point higher. Top 10% is a fair rounded description of both. The label changes at 120 only because a boundary has to be drawn somewhere.

How test manuals label 121.

Professional tests describe score ranges with standard labels. On the WAIS-IV, 121 falls in the superior range; the newer WISC-V calls the same range very high. The labels describe ranges on those specific tests and change at fixed boundaries, so a score a point or two from an edge is not meaningfully different from one just across it.

Descriptive classifications used by the WAIS-IV and WISC-V
Score range	WAIS-IV label	WISC-V label
130 and above	Very superior	Extremely high
120–129 (121)	Superior	Very high
110–119	High average	High average
90–109	Average	Average
80–89	Low average	Low average
70–79	Borderline	Very low
69 and below	Extremely low	Extremely low

High-IQ societies such as Mensa admit people who score at or above the 98th percentile on an approved, supervised test, roughly 130 on an SD-15 scale. Online estimates, including IQInsight’s, do not count toward membership.

How precise is one result?

Every test score contains some measurement error. Professionally normed tests report a confidence interval, a band of several points around the score, and two results a few points apart often overlap. IQInsight has not been calibrated against a representative population, so it cannot provide a reliable interval for its estimates.

How the percentile is calculated.

The reference uses a mean of 100 and a standard deviation of 15. First convert the score to a z-score, then find the area below it on the standard normal curve.

z = (121 − 100) ÷ 15 = 1.4000

Percentile = Φ(z) × 100 ≈ 91.92%

At or above = (1 − Φ(z)) × 100 ≈ 8.08%

Approximate rarity = 1 ÷ (1 − Φ(z)) ≈ 1 in 12

Calculations use full precision before rounding. Φ is the cumulative standard normal distribution; the NIST statistical handbook explains this mathematical function. This reference does not validate IQInsight or any individual test.

Explore an IQ score

High range on the reference scale

91.92%theoretical percentile

1 in 12at this score or higher

Theoretical normal distribution. Mean 100, standard deviation 15. This does not measure your IQ or compare you with IQInsight users.

Put the number in perspective.

In a normal distribution with mean 100 and standard deviation 15, about 8.08% of scores fall at or above 121. That is approximately one in 12. The figure describes the reference model; it is not a count of people we have tested.

The quality of the test matters.

A number alone does not show how accurately it was measured. An established, professionally administered test has supporting evidence and defined interpretation rules. An online exercise without representative norms cannot establish the same conclusions.

Nearby scores on the same scale.

Theoretical percentiles, mean 100 and standard deviation 15
Score	Theoretical percentile	At or above
112	78.81%	21.19%
115	84.13%	15.87%
118	88.49%	11.51%
120	90.88%	9.12%
121 (this page)	91.92%	8.08%
124	94.52%	5.48%
125	95.22%	4.78%
126	95.85%	4.15%
127	96.41%	3.59%

See all 25 score guides. For values between these guides, use the calculator above or the full IQ chart.

What can you do with a score of 121?

A 121 is a high result on the reference scale. Use the component results of the test, rather than the label, to decide what to practise or explore next.

Read how IQInsight handles estimates

A reasoning example to explore.

A score alone cannot tell you how a person thinks through a problem. This published sample illustrates a reasoning method; it is not calibrated to a 121 IQ level and does not predict a score.

Double the current term, then add the next counting number, starting with +1: 3, 7, 16, 35, 74. What comes next?

A. 148
B. 149
C. 152
D. 153

Reveal the answer and reasoning

Answer: 153. The additions are +1, +2, +3 and +4. The next transition is 74×2+5=153.

Check an alternative: 148. Doubling 74 leaves out the addition.

Try this approach. Write both parts of every transition and advance the changing part.

This is one of our public sample questions. Seeing the solution may make a future attempt more familiar. Explore the sample report to see how answers are explained.

A few things you might be wondering.

Clear answers, before you begin.

Is 121 in the top 10%?

On the mean-100, SD-15 model, yes: about 8.08% of values are at or above 121. That is a statement about the reference scale. Whether a particular test supports placing you there depends on its norms and precision.

What percentile is an IQ of 121?

On a scale with mean 100 and standard deviation 15, 121 is at roughly the 92nd percentile: about 8.08% of values are at or above it. Tests with a different standard deviation give a different percentile for the same number.