Normal Distribution Z-Score Calculator
Turn a value into a z-score and report its probability and percentile.
What is Normal Z-Score?
A z-score is the number of standard deviations a value sits from the mean, z = (x − μ) ÷ σ. This page is the normal-distribution half of the Number Theory z-score page: it computes z the same way and then goes on to the probability and percentile that a normal-distribution question asks for.
How it works
After standardising the value, the standard normal CDF turns z into an area, and the left tail, right tail and two-tailed p-value are read from it. The standard normal curve with the region shaded makes the percentile a picture rather than a table lookup.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.