Confidence Interval Calculator
Calculate confidence intervals for means, proportions, and differences
Instructions
1.Select the type of confidence interval (Mean, Proportion, or Difference)
2.Choose your desired confidence level
3.Enter the required sample statistics
4.Click “Calculate Interval” to get results
Confidence Levels
90%: z = 1.645
95%: z = 1.96 (most common)
99%: z = 2.576
99.9%: z = 3.291
Interpretation
A confidence interval provides a range of plausible values for a population parameter.
The confidence level represents the percentage of intervals that would contain the true parameter if we repeated the sampling process many times.