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IQ Score Chart: Wechsler Bell Curve, Percentiles & Scale Ranges

Explore the complete IQ score chart for the Wechsler (WAIS-IV) scale, including standard deviation bell curve percentiles, average ranges, and classifications.

Based on Multi-Index Cognitive Assessment & Fluid-Crystallized Reasoning Model

Developed by David Wechsler, Ulric Neisser & Ian J. Deary (1955 / 1996 / 2010)

A multi-dimensional psychometric framework evaluating adult cognitive problem-solving across verbal comprehension, perceptual matrix reasoning, working memory, and processing speed.

Author: TesVia Editorial Team·Reviewed: TesVia Editorial Team·Published: Nov 2026·Last reviewed: Nov 2026

An educational cognitive reasoning practice test across verbal, matrix, working-memory, and quantitative items. Does not replace a proctored clinical WAIS-IV evaluation.

In one sentence

On a standardized adult IQ score chart—such as the Wechsler Adult Intelligence Scale (WAIS-IV)—scores follow a normal Gaussian bell curve with an average (mean) of 100 and a standard deviation of 15. Roughly 68% of all adults score within one standard deviation of the mean (85 to 115), while a score of 130 (+2 SD) places an individual in the 98th percentile.

Complete Wechsler (WAIS-IV) IQ Score Chart & Classifications

Modern psychometric tests use Deviation IQ rather than ratio IQ. With a mean of 100 and a standard deviation (SD) of 15, the official Wechsler descriptive classifications break down into seven bands:

  • 130 and Above (Very Superior — +2.0 SD): 98th to 99.9th percentile (~2.2% of the population). Typical threshold for Mensa eligibility on an SD-15 scale.
  • 120 – 129 (Superior — +1.33 to +1.93 SD): 91st to 97th percentile (~6.7% of the population). Reflects strong abstract synthesis and rapid problem-solving.
  • 110 – 119 (High Average — +0.67 to +1.27 SD): 75th to 90th percentile (~16.1% of the population).
  • 90 – 109 (Average — -0.67 to +0.60 SD): 25th to 74th percentile (exact middle 50% of all adults).
  • 80 – 89 (Low Average): 9th to 24th percentile (~16.1% of the population).
  • 70 – 79 (Borderline): 2nd to 8th percentile (~6.7% of the population).

Why Does the Same Percentile Look Different on Different IQ Scales?

When comparing a score on an IQ score chart, always check the test’s Standard Deviation (SD):

  1. SD = 15 (Wechsler WAIS-IV, WISC-V, Stanford-Binet SB5): The 98th percentile (+2 SD) equals 130, and the 99.9th percentile (+3 SD) equals 145.
  2. SD = 16 (Older Stanford-Binet Forms): The 98th percentile (+2 SD) equals 132, and +3 SD equals 148.
  3. SD = 24 (Cattell Culture Fair III): The 98th percentile (+2 SD) equals 148. A score of 148 on a Cattell scale represents the exact same 98th percentile as a 130 on a Wechsler test.

Why Psychologists Look at the 4 Index Scores—Not Just Full-Scale IQ

In a clinical Wechsler profile, two people with the exact same Full-Scale IQ (FSIQ) of 115 can have completely different cognitive architectures:

  • Verbal Comprehension Index (VCI): Measures crystallized vocabulary, conceptual similarities, and verbal reasoning.
  • Perceptual Reasoning Index (PRI): Measures fluid non-verbal matrix logic and spatial visualization.
  • Working Memory Index (WMI): Measures mental arithmetic and alphanumeric sequence manipulation.
  • Processing Speed Index (PSI): Measures rapid visual scanning and symbol coding under time constraints.

Frequently Asked Questions

What is a good IQ test score vs. a great IQ test score?

On an SD-15 Wechsler IQ chart, 90 to 109 is the normative Average range (middle 50% of adults), 110 to 119 is High Average (top 25%), 120 to 129 is Superior (top 9%), and 130 or higher (+2 SD) is Very Superior (top 2.2%).

What is the IQ test scale standard deviation on the WAIS-IV?

The Wechsler Adult Intelligence Scale (WAIS-IV) uses a population mean of 100 and a standard deviation (SD) of 15. Each 15-point step above or below 100 represents one full standard deviation along the Gaussian bell curve.

Can your score on an IQ chart change as you get older?

Because Deviation IQ compares you strictly against peers in your own age group, your scaled score remains remarkably stable across adulthood. Furthermore, while raw processing speed peaks in the twenties, verbal comprehension and crystallized expertise continue rising into middle age.

Where can I practice Wechsler-style matrix and verbal reasoning questions?

You can take our free 10-question Wechsler IQ Test Practice Assessment on TesVia to explore your strengths across matrix progressions, verbal similarities, and working memory.

Important Notice

This test is informed by published psychological research and designed for self-reflection and educational purposes. It does not provide medical or psychological diagnosis.

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