Statistics

Confidence Interval

What is the Confidence Interval?

Range estimate for population mean

This formula is widely used in statistics applications. Understanding when and how to apply it helps you interpret calculator results correctly and catch input errors before they propagate.

Formula

CI = mean +/- z * (s/sqrt(n))

Substitute known values into the formula above. Ensure all variables use consistent units before calculating.

Worked Example

95% confidence uses z about 1.96

Use the linked calculator below to try your own values and see step-by-step working.

When to Use This Formula

Apply the Confidence Interval when you need to range estimate for population mean. It is a standard reference in statistics coursework, professional practice, and our linked calculators.

Tips & Common Mistakes

  • Confirm whether you need sample or population formulas.
  • Report spread measures alongside averages.
  • Always verify critical results independently for engineering, medical, or legal applications.

Related Calculators

Confidence Interval Calculator

Use online tool

Further Reading

Browse the Formula Library for related formulas, or read educational articles on our Blog.