Confidence Interval Calculator
Calculate confidence intervals for means (Z or t) and proportions with any confidence level.
95% Confidence Interval
Lower bound
46.2653
Upper bound
53.7347
Standard error: 1.825742
Critical value: 2.0456
Margin of error: 3.7347
Interval width: 7.4695
What is a confidence interval?
A confidence interval gives a range of plausible values for a population parameter. A 95% CI means that if the sampling procedure were repeated many times, 95% of the computed intervals would contain the true parameter. For unknown σ, use the t-interval; for known σ or large n (>30), the Z-interval is appropriate. Proportion intervals use the Wald method.
Private & free — this tool runs entirely in your browser.
Related Calculators tools
Percentage Calculator
Solve percentage, increase, and change calculations.
Age Calculator
Calculate exact age in years, months, and days.
Unix Timestamp Converter
Convert Unix epoch timestamps to and from human dates.
Tip Calculator
Calculate tip and split the bill between people.
Aspect Ratio Calculator
Solve width or height for a target aspect ratio.
Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin.
Data Storage Converter
Convert between bytes, KB, MB, GB, TB, and more.
Discount Calculator
Calculate sale price and savings from a discount.