Statistics calculator
Confidence Interval Calculator
Estimate a confidence interval for a sample mean from mean, standard deviation, sample size, and confidence level.
Formula
Mean confidence interval
This uses a normal approximation and assumes the entered standard deviation is suitable for the sample.
Margin = z x standard deviation / sqrt(sample size)
Mean 50, SD 10, n 100, and 95% confidence gives margin 1.96.
FAQs
What does margin of error mean?+
It is the amount added and subtracted from the sample mean to form the interval.
Which confidence levels are supported?+
The calculator includes common 90%, 95%, and 99% levels.
How does the Confidence Interval Calculator calculate the result?+
It uses the Mean confidence interval: Margin = z x standard deviation / sqrt(sample size). Mean 50, SD 10, n 100, and 95% confidence gives margin 1.96.
What information do I need to use the Confidence Interval Calculator?+
Estimate a confidence interval for a sample mean from mean, standard deviation, sample size, and confidence level.
How accurate is the Confidence Interval Calculator?+
Confidence Interval Calculator applies the formula and assumptions shown on this page. Results may be rounded for readability, so verify changing rates, thresholds, medical guidance, or legal rules with the cited source or a qualified professional.
What should I check before using the Confidence Interval Calculator result?+
Check that the units, dates, rates, and assumptions match your situation. Change one input at a time to understand which values have the largest effect on the result.
Statistics guide
How to use the Confidence Interval Calculator
Estimate a confidence interval for a sample mean from mean, standard deviation, sample size, and confidence level. The page also explains the mean confidence interval and shows a practical example: Mean 50, SD 10, n 100, and 95% confidence gives margin 1.96.
- 1
Enter your details
Enter mean, standard deviation, sample size, and confidence level, then complete any other fields shown in the calculator.
- 2
Check the calculation
Review the result alongside the mean confidence interval: Margin = z x standard deviation / sqrt(sample size).
- 3
Compare scenarios
Change one or more inputs to see how they affect the confidence Interval Calculator result before you use the estimate.
Was this calculator useful?
0/1200