Normal Distribution Calculator
Calculate probabilities for the normal (Gaussian) distribution. Find the probability that a value falls below, above, or between two points on the bell curve.
The normal distribution (bell curve) is the most important distribution in statistics.
PDF (Probability Density Function): f(x) = (1 / (σ√(2π))) × e^(-(x-μ)²/(2σ²))
CDF (Cumulative Distribution Function): P(X ≤ x) = Φ((x - μ) / σ)
where Φ is the standard normal CDF.
68-95-99.7 Rule
- 68% of data falls within 1σ of the mean
- 95% within 2σ
- 99.7% within 3σ