Confidence Interval Calculator

Calculate confidence intervals for population parameters including means, proportions, and differences with detailed statistical analysis.

Confidence Interval Parameters

Configure your statistical parameters for confidence interval calculation

Parameter Type

Confidence Level (%)

Sample Size (n)

Sample Mean (x̄)

Sample Std Dev (s)

Population Std Dev (σ) - Optional

Use Z-distribution if known, t-distribution if unknown

Quick Examples:

Confidence Intervals Fundamentals

What is a Confidence Interval?

A confidence interval is a range of values that likely contains the true population parameter. It provides both an estimate and a measure of uncertainty about that estimate.

Key Components

Point Estimate: The best single guess for the parameter (sample mean, proportion, etc.)

Margin of Error: The maximum expected difference between the point estimate and true parameter

Confidence Level: The probability that the method produces intervals containing the true parameter

Critical Value: The multiplier from the appropriate distribution (Z or t)

General Formula

CI = Point Estimate ± (Critical Value × Standard Error)