OceanCalc

Z-Score Calculator

Calculate z-scores and find probabilities using the standard normal distribution.

Calculator Mode
Parameters

The value to convert to z-score

The average of the population

The standard deviation of the population

Z-Score Formula

z = (x - μ) / σ

The z-score indicates how many standard deviations a value is from the mean. A positive z-score means above average, negative means below average.

Common Z-Scores:

  • z = 0 → 50th percentile (mean)
  • z = 1 → 84th percentile
  • z = 2 → 97.7th percentile
  • z = -1 → 16th percentile

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Z-Score Results
Z-Score-1
Percentile15.87%
P(X < x)0.1587
P(X > x)0.8413