Free IQ Percentile Calculator

The IQ to Percentile Calculator converts an Intelligence Quotient (IQ) score into its corresponding percentile rank, giving you a clear picture of how your cognitive ability compares with the general population. The IQ percentile tells you the percentage of people who score at or below your level, making it easy to interpret results from standardized IQ tests. This tool also provides an IQ Percentile Chart and IQ Classification tables to help you understand the meaning of different score ranges.

Understanding IQ and Percentiles

IQ stands for Intelligence Quotient, a standardized score derived from tests designed to measure fluid intelligence — the ability to reason, learn new concepts, recognize patterns, and solve problems. Historically, IQ was computed as (mental age ÷ chronological age) × 100, which is why the term “quotient” persists. Modern assessments use deviation IQ, where raw scores are transformed to a normal distribution with a mean of 100 and a standard deviation (SD) of either 15 (most common, used by Wechsler and SB5) or 16.

A percentile rank indicates the proportion of a reference group that scores at or below a given IQ score. For example, an IQ score of 70 corresponds to the 2nd percentile (SD = 15), meaning only 2% of the population scores 70 or lower. Conversely, an IQ of 125 is at the 95th percentile — 95% of people score at or below 125, and only 5% score higher. Converting an IQ score to its percentile is a direct way to see where you stand relative to others.

The Distribution of IQ Scores

IQ scores in the general population follow a bell‑shaped normal distribution. Applying the empirical rule (68‑95‑99.7) to this distribution:

• Roughly 68% of people have an IQ between 85 and 115 (within one standard deviation of the mean).
• About 95% fall between 70 and 130 (within two SDs).
• Approximately 99.7% score between 55 and 145 (within three SDs).

This pattern shows that most individuals cluster near the average, with relatively few at the extreme high or low ends. In practical terms, there are many average scorers, a small number of gifted individuals, and a similarly small number of individuals with intellectual disabilities.

How to Use the IQ Percentile Calculator

Before using the calculator, you need a reliable IQ score obtained from a professionally administered test. Common standardized tests include:

• Wechsler Adult Intelligence Scale (WAIS)
• Wechsler Intelligence Scale for Children (WISC)
• Stanford‑Binet Intelligence Scale
• Cattell Culture Fair Intelligence Test
• Universal Nonverbal Intelligence Test
• Differential Ability Scales (DAS)
• Woodcock‑Johnson Tests of Cognitive Abilities

Once you have your score, follow these steps:

1. Enter your IQ score into the calculator.
2. Select the standard deviation used by your test (the default is 15; you can switch to 16 using the radio buttons).
3. The calculator instantly displays your percentile rank and a brief interpretation.

The tool also shows a visual distribution chart: scores below yours are colored red, scores above in blue. The X‑axis represents IQ scores, and the Y‑axis shows the percentage of the population at each score. For instance, you can see that roughly 2.7% of the population has an IQ of exactly 100.

Note that different IQ tests may have different valid score ranges. The chart assumes a typical range and may not be reliable for scores outside that range.

IQ Percentile Reference Table

The following table (calculated for SD = 15) gives the percentile rank for various IQ scores:

IQ Score	Percentile
20	0.000004
30	0.0002
40	0.003
50	0.04
60	0.4
70	2
80	9
90	25
100	50
110	75
120	91
130	98
140	99.6
150	99.96
160	99.997
170	99.99985
180	99.999996

Scores of 130 and above are at the 98th percentile or higher, meaning they fall within the top 2% of the population. Conversely, scores below 70 are in the bottom 2%.

IQ Classification Standards

Different IQ tests employ slightly different classification labels. Below are four commonly referenced systems.

Wechsler (WAIS‑IV / WPPSI‑IV) Classification

IQ Range (Deviation IQ)	Classification
130 and above	Very Superior
120–129	Superior
110–119	High Average
90–109	Average
80–89	Low Average
70–79	Borderline
69 and below	Extremely Low

Stanford‑Binet Fifth Edition (SB5) Classification

IQ Range (Deviation IQ)	Classification
144+	Very Gifted or Highly Advanced
130–144	Gifted or Very Advanced
120–129	Superior
110–119	High Average
90–109	Average
80–89	Low Average
70–79	Borderline Impaired or Delayed
55–69	Mildly Impaired or Delayed
40–54	Moderately Impaired or Delayed

Woodcock‑Johnson III (WJ III) Classification

IQ Score	Classification
131 and above	Very Superior
121–130	Superior
111–120	High Average
90–110	Average
80–89	Low Average
70–79	Low
69 and below	Very Low

DAS‑II (2007) General Conceptual Ability (GCA) Classification

GCA Score	Classification
≥ 130	Very High
120–129	High
110–119	Above Average
90–109	Average
80–89	Below Average
70–79	Low
≤ 69	Very Low

These classification tables provide context for raw IQ scores. Keep in mind that the exact labels vary by test, but the underlying interpretation is similar: higher scores indicate superior cognitive ability relative to the general population.

Important Considerations

This IQ percentile calculator offers a quick and accurate estimate based on standard norms, but it should not replace a comprehensive professional evaluation. Cognitive assessment involves multiple factors beyond a single IQ score. Additionally, the calculator assumes a standard deviation of 15 unless you adjust it; using an incorrect SD will yield inaccurate percentiles. Always refer to the official test manual to confirm the appropriate SD for the instrument you took.

The IQ‑to‑percentile values in the reference table are calculated for SD = 15 and may not correspond exactly to tests that use SD = 16. If your test uses a different SD, be sure to change the setting in the calculator accordingly. Finally, remember that no online tool can substitute for a face‑to‑face evaluation by a qualified psychologist.