Statistics calculator

Z Score Calculator

Standardize a raw value or reverse a z-score with a clearly defined mean and positive standard deviation.

Enter values and select Calculate.

Formula and methodology

The z-score is z = (x − μ) / σ. Reverse mode uses x = μ + zσ. Standard deviation must be greater than zero.

Worked example

For x = 85, μ = 70, and σ = 10, z = 1.5.

Assumptions and interpretation

Inputs and results remain in this browser and are not sent to analytics.
This tool performs general educational statistical computation; it does not select a study design or validate scientific conclusions.
Confidence-interval coverage describes repeated use of the method under its assumptions, not a probability assigned to the fixed parameter after calculation.
Keep full precision for decisions; displayed values are rounded for readability.