Normal Distribution Probability Calculator - Free, Instant, In Your Browser
Enter a z-score to calculate the probability that a standard normal random variable is less than or equal to it.
How to use Normal Distribution Probability Calculator
- 1Paste your text or data into the input box above.
- 2Normal Distribution Probability Calculator runs instantly, right in your browser.
- 3Copy the result or use it directly.
Your file is processed in your browser and is never uploaded.
Frequently Asked Questions
What's the formula?
Computed via the standard normal CDF, Φ(z) = 0.5 x (1 + erf(z / √2)), using a well-known polynomial approximation of the error function.
Is my data sent to a server?
No - everything runs entirely in your browser with JavaScript. Nothing is uploaded.