Z-Score Calculator

Calculate the z-score (standard score) for a given value from its mean and standard deviation.

Raw Score (x)

Population Mean (μ)

Standard Deviation (σ)

Z-Score

Percentile (from z-table)

Probability Above

Probability Below

How It Works

The z-score tells you how many standard deviations a value is from the mean. A positive z-score means the value is above the mean; negative means below. The percentile shows what percentage of the population falls below the given value.

z = (x − μ) / σ | Percentile = Φ(z) × 100

About this Calculator

The Z-Score Calculator is a free, easy-to-use tool for standard, normal, distribution. Simply enter your values and get instant, accurate results — no signup, no ads, no tracking. All calculations run locally in your browser, so your data stays completely private.

Privacy Note: All calculations are performed locally in your browser. No data is ever sent to a server or third party.