Confidence Interval Calculator

Calculate confidence intervals and margin of error based on sample mean, size, and standard deviation—instantly and accurately in your browser.

How to Use Confidence Interval Calculator

1. Enter the Sample Mean (x̄) — this is the average of your data set.

2. Input Sample Size (n) — the total number of observations.

3. Enter Standard Deviation (s) — the variation of your dataset.

4. Choose a Confidence Level — options include 90%, 95%, 99%, 99.9%.

5. Click “Calculate” to view the confidence interval, margin of error, and bounds.

6. Click “Sample” to auto-generate example data, or “Reset” to clear fields.

Confidence Interval Calculator Key Features

• Calculates upper and lower bounds, margin of error, and full confidence interval

• Supports custom sample inputs for x̄, n, s, and confidence level

• Instantly generates results for 99%, 95%, and 90% confidence levels

• Fully browser-based—no installation or external processing

• Easy-to-understand statistical visualization

• Supports education, research, finance, and analytics

Why Confidence Interval Calculator Is Best for Statistical Accuracy

• Removes manual formula work—no z-table or t-table lookup needed

• Supports real-time updates for changing sample inputs

• Helps verify statistical significance in experimental or survey results

• Works for small and large sample sizes

• Ideal for students, researchers, and data professionals

Use Cases of Confidence Interval Calculator

1. Estimate confidence range of a population mean from a small study

2. Calculate error margins for academic or scientific reporting

3. Analyze survey results and produce interval estimates

4. Validate significance in experimental data

5. Teach students how confidence intervals and error margins behave with different inputs

Related Tools

• Average Calculator – Use it to calculate the sample mean before determining confidence intervals.

• Margin Calculator – Determine profit or cost margins alongside statistical margins of error.

• Percentage Calculator – Use it to translate confidence range data into percentage-based insights.

• Probability Calculator – Evaluate likelihoods related to confidence interval outcomes.

• TDEE Calculator – Understand confidence intervals in health data and body metric estimates.

FAQs

What is a confidence interval?

A confidence interval is a range of values that estimates the true population mean, based on a sample.

What does the margin of error mean?

Margin of error reflects how much the sample mean may differ from the true population mean at a given confidence level.

What confidence levels are supported?

You can select standard levels like 90%, 95%, 99%, and 99.9%.

What formula is used?

The calculator uses the standard formula:
CI = x̄ ± z(s/√n)* where z is based on the chosen confidence level.

Can I use this for small samples?

Yes. For small samples, ensure your data is normally distributed for valid results.

Is this calculator accurate?

Yes. It uses exact statistical models to provide precise interval estimates.

Can I generate example values?

Yes. Click the “Sample” button to populate the form with demo inputs.

Does this support t-distribution?

Currently, it uses z-distribution (standard normal). For very small samples, results are approximate.

Are the inputs saved?

No. All data is processed in-browser and cleared when you leave or reset.

Is it free to use?

Yes. The tool is fully free with instant results and no sign-up required.

🔒 Security & Privacy Notes

All calculations are performed directly in your browser—nothing is uploaded.
We do not track, save, or share any of your input values.
Your session is completely private, and all data is cleared on reset or page refresh.
Built with a privacy-first design, this tool ensures data stays on your device.

For more information, view our full Privacy Policy

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