IQ to T-score Score Converter

Convert IQ ↔ T-score

How the conversion works

IQ and T-score scores are normalised on bell-curve distributions. The conversion maps a person's standing in one distribution to the equivalent standing in the other.

• IQ: mean 100, standard deviation 15.
• T-score: mean 50, standard deviation 10. T-scores avoid negative numbers by shifting the mean from 0 to 50. They are common in clinical assessment, the MMPI, the NEO-PI, and similar instruments.

IQ-equivalent = (target − mean_target) / SD_target × 15 + 100
target-equivalent = (IQ − 100) / 15 × SD_target + mean_target

Common IQ ↔ T-score reference table

Important caveats

• IQ and T-scores are mathematically equivalent representations of the same standing on a normal distribution. The conversion is exact (T = (IQ − 100) / 15 × 10 + 50), not an estimate.
• Extreme-tail conversions are less reliable because both tests have fewer calibration cases there.
• No score entered here is stored, submitted, or connected to an account.

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IQ percentile calculator · IQ to Z-score converter · IQ to Stanine converter · IQ score chart