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Confidence Interval Calculator

Compute the lower and upper bounds of a confidence interval for a population mean using a sample mean, the standard error of that mean, and a critical z-value (1.645 / 1.96 / 2.576 for 90% / 95% / 99% confidence). This is the standard way to report uncertainty around survey results, lab measurements, or any sample-based estimate.

Sample Mean

Standard Error

Z-Value

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Statistics

Standard Error Calculator

Compute the standard error of the mean (SEM) from the sample standard deviation and sample size, SEM = s/√n. Quantifies how precisely a sample mean estimates the underlying population mean — the foundation of confidence intervals, t-tests, and any inferential statistic.

Standard Deviation

Sample Size

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Key differences

	Confidence Interval Calculator	Standard Error Calculator
Category	Statistics	Statistics
Inputs required	3	2
Result	Lower Bound	Standard Error
What it does	Compute the lower and upper bounds of a confidence interval for a population mean using a sample mean, the standard error of that mean, and a critical z-value (1.645 / 1.96 / 2.576 for 90% / 95% / 99% confidence). This is the standard way to report uncertainty around survey results, lab measurements, or any sample-based estimate.	Compute the standard error of the mean (SEM) from the sample standard deviation and sample size, SEM = s/√n. Quantifies how precisely a sample mean estimates the underlying population mean — the foundation of confidence intervals, t-tests, and any inferential statistic.