T-Score Calculator

In this calculator, a T-score is a standardized score with mean 50 and standard deviation 10. It is calculated as T = ((raw - mean) / SD) x 10 + 50, which rescales a z-score. This psychometric convention is not the same scale as the T-score reported for bone density.

Mathematically they carry the same information: T = z x 10 + 50, so z = (T - 50) / 10. A z-score uses mean 0 and SD 1, which yields decimals and negatives. A T-score uses mean 50 and SD 10, which keeps almost every observation positive and easier to talk about with non-statisticians. Use the z-score for textbook probability work and the T-score for psychometric or clinical reporting.

On the mean-50, SD-10 scale used here, a T-score of 65 is 1.5 standard deviations above the reference mean. Whether that is favorable, unfavorable, or clinically meaningful depends on the specific test, its direction, and its validated cutoffs. Use the interpretation guide supplied with that instrument.

A DEXA T-score reports how many standard deviations bone mineral density differs from a young-adult reference mean. It is not transformed to a mean of 50 and SD of 10, so this psychometric T-score calculator is not suitable for interpreting DEXA results. Use the report and a qualified clinician for bone-density assessment.

Yes, for the mean-50, SD-10 scale used here and when you know the reference mean and standard deviation. The inverse formula is raw = ((T - 50) / 10) x SD + mean. Do not apply this formula to other measures that also use the name T-score, including DEXA bone-density scores.