Free IQ Calculator
Estimate IQ with either the classic mental age formula or a standard score conversion. This is an educational tool, not a clinical diagnosis.
Tip: For modern tests, the standard score method is usually more appropriate than mental-age estimates.
What This IQ Calculator Does
An IQ (Intelligence Quotient) score is a standardized way to compare cognitive test performance. This page gives you two methods to estimate IQ, depending on the type of data you have available.
- Mental Age Method: Uses the classic formula: IQ = (Mental Age / Chronological Age) × 100.
- Standard Score Method: Converts any score into IQ format using a mean of 100 and standard deviation of 15.
How to Use the Calculator
Option 1: Mental Age Method
Enter a person’s chronological age and estimated mental age. The calculator multiplies the ratio by 100 to create an IQ-style value. This approach is mostly historical and often less accurate for adults.
Option 2: Standard Score Method
If you have a test score and the test’s distribution data, enter your score, the population mean, and standard deviation. The tool calculates a z-score and converts it to an IQ metric:
IQ = 100 + 15 × ((Your Score − Mean) / Standard Deviation)
How to Interpret the Result
IQ scores are often grouped into broad ranges. These ranges can vary slightly between publishers, but a common interpretation is:
- Below 70: Very low range
- 70–84: Below average
- 85–114: Average range
- 115–129: Above average
- 130+: Very high range
The calculator also estimates a percentile rank, which helps explain relative standing in a population.
Important Limitations
1) Online Calculators Are Not Official Tests
This tool does not replace a professionally administered intelligence test. Clinical and educational decisions should rely on validated instruments and qualified interpretation.
2) IQ Is Not the Whole Person
Human ability includes creativity, practical judgment, emotional regulation, motivation, social understanding, and domain-specific skill. IQ captures only part of cognitive performance.
3) Context Matters
Sleep, stress, language familiarity, educational background, and testing conditions can all influence scores. One number should never be treated as a complete measure of potential.
Frequently Asked Questions
Is this calculator accurate?
It is mathematically accurate for the formulas used. However, the quality of the estimate depends on the quality of your input data.
Can adults use the mental age method?
Not reliably. The mental age formula is primarily historical and can be misleading for adults. Standardized test conversions are generally more meaningful.
What is a “good” IQ score?
In most populations, 100 is average by definition. Higher scores can indicate stronger performance on specific cognitive tasks, but they do not guarantee life outcomes.
Bottom Line
Use this IQ calculator as a quick educational estimate. If you need an official assessment for school, work, or clinical use, seek a licensed psychologist using a validated, supervised testing process.