Confidence Interval Calculator
Estimate a confidence interval for a sample mean with z or t assumptions.
Margin of error
1.96
Lower bound
48.04
Upper bound
51.96
Critical value
1.96
Standard error
1
Assumption
Z interval assumes a known population standard deviation or large-sample normal approximation.
Confidence interval method
Documents the assumptions used for this interval.
| Item | Value |
|---|---|
| Method | Z interval |
| Confidence level | 95% |
| Sample size | 64 |
| Degrees of freedom | Not used |
| Critical value | 1.96 |
| Standard error | 1 |
Formula
Margin of error = critical value × standard error, where standard error = sample standard deviation / sqrt(n). Interval = mean ± margin of error.
Estimate a confidence interval for a sample mean with z or t assumptions.
How to Use
Estimate a confidence interval for a sample mean with z or t assumptions. Fill in Sample mean, Sample standard deviation, Sample size, Confidence level, and Interval method, then review the calculated Margin of error, Lower bound, Upper bound, Critical value, Standard error, and Assumption.
- Open the calculator : Start with Confidence Interval Calculator.
- Enter values : Fill in the required inputs and any optional settings.
- Review the result : Read the output and use the about page for more detail if needed.
Common Questions
What formula does the Confidence Interval Calculator use?
Margin of error = critical value × standard error, where standard error = sample standard deviation / ?(n). Interval = mean ± margin of error.