Confidence Interval Calculator
CI = Mean ± Z × (StdDev ÷ √n)ME=1.96×10÷√100=1.96; CI=[48.04, 51.96]
Free online tool
Confidence Interval Calculator
Enter the sample mean, standard deviation, sample size and confidence level.
Instant calculation
Confidence Interval Calculator
Enter the sample mean, standard deviation, sample size and confidence level.
Your result
Calculation
Your numbers stay in this browser. Nothing is uploaded or saved.
Three clear steps
How to use this calculator
- 01
Enter sample mean
Type the average of your sample.
- 02
Enter standard deviation
Type the sample standard deviation.
- 03
Enter sample size and confidence
Provide the number of observations and confidence level.
The formula
How this calculation works
For 95% confidence, Z=1.96. For 99%, Z=2.576. The interval estimates where the population mean likely falls.
Check the method
Worked examples
Each example follows the same formula used by the calculator.
Mean=50, SD=10, n=100, 95% confidence — interval?
ME=1.96×10÷√100=1.96; CI=[48.04, 51.96][48.04, 51.96]Common questions
Questions about this calculation
What is the Confidence Interval Calculator?
The Confidence Interval Calculator helps you calculate the confidence interval for a population mean. Enter your values and select Calculate to get an instant result.
How is the result calculated?
For 95% confidence, Z=1.96. For 99%, Z=2.576. The interval estimates where the population mean likely falls.
Can you show an example?
Example: Mean=50, SD=10, n=100, 95% confidence — interval? — [48.04, 51.96].
Is my data saved when I use the Confidence Interval Calculator?
No. All calculations run locally in your browser. Your inputs and results are never uploaded, stored or shared with anyone.
Is the Confidence Interval Calculator free to use?
Yes. The Confidence Interval Calculator is completely free. No account, sign-up or payment is required. It works on mobile, tablet and desktop.
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