Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Normal Distribution Calculator

Find the cumulative probability P(X ≤ x) for a normal distribution given any mean, standard deviation, and x value. Useful for statistics students, researchers, and engineers working with continuous random variables.

Mean (μ)

Standard Deviation (σ)

X Value

Decimal Places

Fill in the required fields to see your result.

Statistics

Confidence Interval Calculator

Compute the margin of error around a sample mean for a 90%, 95%, or 99% confidence interval using the z-distribution. The half-width of the CI tells you how precisely your sample estimates the population mean — essential for survey reporting, scientific publication, and any inference.

Sample Size (n)

Standard Deviation

Confidence Level

Fill in the required fields to see your result.

Key differences

	Normal Distribution Calculator	Confidence Interval Calculator
Category	Statistics	Statistics
Inputs required	4	3
Result	Probability	Margin of Error (±)
What it does	Find the cumulative probability P(X ≤ x) for a normal distribution given any mean, standard deviation, and x value. Useful for statistics students, researchers, and engineers working with continuous random variables.	Compute the margin of error around a sample mean for a 90%, 95%, or 99% confidence interval using the z-distribution. The half-width of the CI tells you how precisely your sample estimates the population mean — essential for survey reporting, scientific publication, and any inference.