Z-Score Calculator
Calculate standard scores, percentiles, and raw scores
Instructions
1.Select calculation type (Score to Z-Score, Z-Score to Score, or Percentile to Score)
2.Enter the population mean and standard deviation
3.Enter the value you want to convert
4.Click “Calculate” to get results
Z-Score Formula
Z = (X - μ) / σ
Z: Z-score (standard score)
X: Raw score
μ: Population mean
σ: Population standard deviation
Interpretation
|Z| < 1: Common (within 1 SD)
1 ≤ |Z| < 2: Somewhat unusual
2 ≤ |Z| < 3: Unusual
|Z| ≥ 3: Very unusual