Our IQ Test Methodology

Our Methodology

How questions are designed, how raw answers become a score, and what that score does and doesn’t mean.

Question Design

Each question on the core test is written to target exactly one of four reasoning categories, spatial, numerical, logical, or applied, at one of nine difficulty tiers. Across the full 36-question set, every category appears once per tier, so the final composite score is never skewed toward one type of reasoning simply because it had more questions.

Difficulty tiers are calibrated by construction rather than after-the-fact: early tiers use short sequences and simple one-step logic, while later tiers require multi-step inference, larger working-memory load, or less intuitive numerical relationships.

Scoring Formula

Each answer is scored as correct or incorrect, weighted by its difficulty tier. Your raw result is the weighted share of total possible points earned across all 36 questions, not a simple count of correct answers.

That weighted fraction is converted to a z-score using the inverse cumulative distribution function of the standard normal distribution, then rescaled to a mean of 100 and a standard deviation of 15, the convention used across most published cognitive assessments. This is the same conversion formula, applied consistently, across every scored tool on this site.

What the Score Does Not Measure

A 25-minute, untimed, self-administered online test cannot replicate the controlled conditions of a proctored clinical assessment, which also evaluates factors like verbal comprehension and working memory span through methods a web format cannot reproduce.

Treat your result as a well-grounded estimate of fluid reasoning ability on the day you took it, not a clinical diagnosis. See our about page for more on our editorial standards, or read a sample results report.

The Normal Distribution, Visually

This same distribution model is what powers our IQ score chart and every individual score lookup page, converting any raw score into both a classification band and an exact percentile.

Why We Chose This Scale

We deliberately matched the mean-100, standard-deviation-15 convention used by the Wechsler Adult Intelligence Scale and most other major cognitive assessments, rather than inventing our own scale. This makes a score from our test directly comparable, in a general sense, to scores reported by other tests and sources that follow the same widely used standard, rather than requiring readers to learn a new, site-specific scoring system.

Updates and Transparency

If we ever materially change the question set, scoring weights, or difficulty calibration, we will update this page to reflect the change. Our goal is for this methodology page to always accurately describe exactly how the live test works, not a simplified or outdated summary of it.