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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.

Probability

Hypothesis Test Calculator

Run a one-sample z-test or t-test to determine whether a sample mean significantly differs from a hypothesized population mean. Essential for quality control, clinical trials, and academic research.

Sample Mean

Hypothesized Mean (μ₀)

Sample Standard Deviation

Sample Size (samples)

Fill in the required fields to see your result.

Key differences

	Confidence Interval Calculator	Hypothesis Test Calculator
Category	Statistics	Probability
Inputs required	3	4
Result	Margin of Error (±)	Test Statistic
What it does	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.	Run a one-sample z-test or t-test to determine whether a sample mean significantly differs from a hypothesized population mean. Essential for quality control, clinical trials, and academic research.