Z-Score Calculator

Calculate Z-scores, convert to values, find percentiles — with visual normal distribution curves and detailed explanations.

Z-Score & Percentile

Select calculation mode

Calculation Mode

Value (X)

Z-Score

Percentile (%)

Mean (μ)

Standard Deviation (σ)

Result

Z-Score

Percentile

Select a mode, enter values, and tap Calculate.

Normal Distribution Curve

Step-by-step Solution

Key Formulas

Z = (X − μ) / σ

X = μ + Z × σ

P(X < x) = Φ(z)

Common Z-Scores

Z Percentile

−3.00.13%

−2.02.28%

−1.015.87%

0.050.00%

1.084.13%

1.64595.00%

1.9697.50%

2.57699.50%

Related Calculators