About this tool
Standardise a value and find its percentile under the normal distribution.
z = (x − μ) ÷ σ. The percentile is Φ(z), the standard normal cumulative probability, computed from the error function.
Formula: z = (x − μ)/σ · P = Φ(z)
Example: Value (x) = 85, Mean (μ) = 70, Standard deviation (σ) = 10 → Z-score = 1.5, Percentile (below x) = 93.319%.
The percentile is only meaningful if the data are roughly normally distributed.
Quick steps
- Enter your values — every field shows its unit.
- Press Calculate (or Try an example to see how it works).
- Read the results and copy them if you need them elsewhere.
The calculation runs in your browser. Nothing you type is sent to 1CLIK.
FAQ
How does the Z-score Calculator work?
z = (x − μ) ÷ σ. The percentile is Φ(z), the standard normal cumulative probability, computed from the error function.
What should I keep in mind?
The percentile is only meaningful if the data are roughly normally distributed.
Is my data sent anywhere?
No. The numbers stay on your device; the page only shows the result.