IQ Levels Chart: Understanding Intelligence Test Scores
Author: Ian C. Langtree - Writer/Editor for Disabled World (DW)
Published: 2014/08/06 - Updated: 2026/01/18
Publication Type: Charts, Graphs, Tables
Category Topic: Calculators - Charts - Related Publications
Page Content: Synopsis - Introduction - Main - Insights, Updates
Synopsis: This information offers detailed insight into intelligence quotient testing, score interpretation, and classification systems used by test publishers worldwide. The material proves particularly valuable for individuals trying to understand cognitive assessment results, whether for educational planning, disability evaluations, or personal knowledge. By presenting the statistical distribution of IQ scores across populations - from genius level (144+) to low ranges (below 55) - alongside explanations of deviation IQ scoring methods and normal distribution patterns, readers gain context for interpreting test results. The resource addresses practical concerns about test reliability, score variation over time, and limitations of IQ measurements, making technical psychometric concepts accessible to general audiences including families navigating special education services, adults seeking cognitive assessments, and anyone curious about how intelligence testing actually works - Disabled World (DW).
- Definition: Intelligence Quotient (IQ)
Intelligence Quotient, or IQ, is a standardized score derived from tests designed to measure human cognitive abilities relative to age-matched peers. The concept emerged in the early 20th century when psychologists needed a way to compare mental capabilities across individuals, and it's calculated by dividing a person's mental age (as determined by test performance) by their chronological age, then multiplying by 100 - though modern tests use statistical normalization instead. A score of 100 represents the average, with most people falling between 85 and 115, while scores above 130 are considered significantly above average and those below 70 significantly below.
IQ tests typically assess various cognitive domains including logical reasoning, mathematical ability, spatial visualization, verbal comprehension, and processing speed, though critics rightly point out that these tests don't capture creativity, emotional intelligence, practical problem-solving, or the full spectrum of human mental capacity. The score has proven useful in educational and clinical settings for identifying learning disabilities or giftedness, but it's become controversial due to historical misuse in justifying discrimination and ongoing debates about cultural bias in testing methods. While IQ shows moderate heritability and correlates with academic and professional success, it's neither fixed nor deterministic - environmental factors like education, nutrition, and intellectual stimulation significantly influence scores, and intelligence itself manifests in countless ways that no single number can adequately represent.
Introduction
Intelligence Quotient (IQ) is defined as the number representing a person's reasoning ability (measured using problem-solving tests) as compared to the statistical norm or average for their age, taken as 100. The abbreviation "IQ" was coined by the psychologist William Stern for the German term Intelligenz-quotient, his term for a scoring method for intelligence tests he advocated in a 1912 book.
IQ classification is the practice by IQ test publishers of labeling IQ score ranges with category names such as "superior" or "average". There are several publishers of IQ tests. No two publishers use exactly the same classification labels. IQ classification labels have changed from time to time since the beginning of IQ testing in the early twentieth century.
- Mensa: An international fellowship organization for people with IQ's in the top 2% of the general population, is the largest and oldest high IQ society in the world with national groups in fifty countries.
- EQ: A measure of a person's level of emotional intelligence. Some psychologists believe that standard measures of intelligence (IQ scores) are too narrow and do not encompass the full range of human intelligence. Instead, they suggest, the ability to understand and express emotions can play an equal if not even more important role in how people fare in life.
- Flynn Effect: The fact that each generation scores higher on an IQ test than the generation before it. Are we actually getting smarter, or just thinking differently?
- Genius IQ: Generally, any score over 140 is counted as a high IQ. A score over 160 is considered by many to be a genius IQ score.
Main Content
Critics point out that IQ tests don't measure creativity, social skills, wisdom, acquired abilities or a host of other things we consider to be aspects of intelligence. Although IQ attempts to measure some notion of intelligence, it may fail to act as an accurate measure of "intelligence" in its broadest sense. IQ tests only examine particular areas embodied by the broadest notion of "intelligence", failing to account for certain areas which are also associated with "intelligence" such as creativity or emotional intelligence.
IQ tests generally are reliable enough that most people ages ten and older have similar IQ scores throughout life. Still, some individuals score very differently when taking the same test at different times or when taking more than one kind of IQ test at the same age. Intelligence test scores typically follow what is known as a normal distribution, a bell-shaped curve in which the majority of scores lie near or around the average score.
The current scoring method for all IQ tests is the "deviation IQ". In this method, an IQ score of 100 means that the test-taker's performance on the test is at the median level of performance in the sample of test-takers of about the same age used to norm the test. An IQ score of 115 means performance one standard deviation above the median, a score of 85 performance one standard deviation below the median, and so on. The average IQ is 100. Most IQ tests are constructed so that there are no overall score differences between females and males.
All IQ tests show variation in scores even when the same person takes the same test over and over again. IQ scores also differ for a test-taker taking tests from more than one publisher at the same age.
Health is important in understanding differences in IQ test scores and other measures of cognitive ability. Several factors can lead to significant cognitive impairment, particularly if they occur during pregnancy and childhood when the brain is growing and the blood-brain barrier is less effective. Such impairment may sometimes be permanent, sometimes be partially or wholly compensated for by later growth.
Cognitive epidemiology is a field of research that examines the associations between intelligence test scores and health. Researchers in the field argue that intelligence measured at an early age is an important predictor of later health and mortality differences.
IQ classification is the practice by IQ test publishers of designating IQ score ranges as various categories with labels such as "superior" or "average." IQ classification was preceded historically by attempts to classify human beings by general ability based on other forms of behavioral observation. Those other forms of behavioral observation are still important for validating classifications based on IQ tests.
Simply put, IQ tests are designed to measure your general ability to solve problems and understand concepts. This includes reasoning ability, problem-solving ability, ability to perceive relationships between things and ability to store and retrieve information. IQ tests measure this general intellectual ability in a number of different ways. They may test:
- Spatial ability: the ability to visualize manipulation of shapes.
- Mathematical ability: the ability to solve problems and use logic.
- Memory ability: the ability to recall things presented either visually or aurally.
- Language ability: Includes the ability to complete sentences or recognize words when letters have been rearranged or removed.
| IQ Grade | IQ Range | Percent of Population |
|---|---|---|
| Genius | 144 | 0.13% |
| Gifted | 130-144 | 2.14% |
| Above average | 115-129 | 13.59% |
| Higher average | 100-114 | 34.13% |
| Lower average | 85-99 | 34.13% |
| Below average | 70-84 | 13.59% |
| Borderline low | 55-69 | 2.14% |
| Low | <55 | 0.13% |
Interested in Your IQ Level?
There are a number of websites online that provide free IQ tests, a simple search for a term such as "Online Free IQ Test" should provide you with a number of options to choose from. Please bear in mind though that not all online IQ tests are accurate or reliable.
Insights, Analysis, and Developments
Editorial Note: Understanding where someone falls on the IQ spectrum matters less than recognizing what these numbers actually represent - and what they don't. While IQ tests measure specific cognitive abilities like problem-solving and pattern recognition with reasonable reliability, they miss entirely other forms of intelligence that shape success and fulfillment in life. Emotional awareness, creative thinking, practical wisdom, and social competence don't show up in these scores, yet they often determine outcomes far more than raw reasoning ability ever could. For people with disabilities, these scores sometimes create barriers when used rigidly in educational or employment settings, rather than serving their intended purpose as one data point among many. The real value in understanding IQ classification lies not in comparing ourselves to statistical norms, but in recognizing our own cognitive strengths and challenges so we can build on what works and find support where needed - Disabled World (DW).
Author Credentials: Ian is the founder and Editor-in-Chief of Disabled World, a leading resource for news and information on disability issues. With a global perspective shaped by years of travel and lived experience, Ian is a committed proponent of the Social Model of Disability-a transformative framework developed by disabled activists in the 1970s that emphasizes dismantling societal barriers rather than focusing solely on individual impairments. His work reflects a deep commitment to disability rights, accessibility, and social inclusion. To learn more about Ian's background, expertise, and accomplishments, visit his full biography.