Confidence Interval Calculator

Confidence Interval Calculator

Calculation Type:

Population Mean (σ known)Z-interval for population mean with known standard deviation

Population Mean (σ unknown)T-interval for population mean with sample standard deviation

Population ProportionZ-interval for population proportion

Sample Mean (x̄):

Sample Size (n):

Population Standard Deviation (σ):

Confidence Level:90%95%99%Custom

Sample Standard Deviation (s):

Confidence Level:90%95%99%Custom

Sample Proportion (p̂):

Confidence Level:90%95%99%Custom

Custom Confidence Level (%):

Options

Show Detailed CalculationDisplay the step-by-step calculation process

Round ResultsRound to decimal places

Decimal Places:

Confidence Interval Result

Detailed Calculation:

Confidence Interval Information:

Perform a calculation to see information

Note: This tool calculates confidence intervals for population parameters with different methods.

About This Confidence Interval Calculator

This calculator computes confidence intervals for population means (with known or unknown standard deviation) and population proportions. It performs all calculations client-side without sending your data anywhere.

How to Use This Calculator

Step-by-Step Guide:

1. Step 1: Select the type of confidence interval you need
2. Step 2: Enter the required parameters (mean, proportion, standard deviation, etc.)
3. Step 3: Select or specify the confidence level
4. Step 4: Choose calculation options
5. Step 5: Click "Calculate" to see results
6. Step 6: View additional information and copy results

Calculation Types:

• Z-Interval (σ known): x̄ ± z*(σ/√n)
• T-Interval (σ unknown): x̄ ± t*(s/√n)
• Proportion Interval: p̂ ± z*√(p̂(1-p̂)/n)

Example Calculations:

Type: Z-Interval (σ known) Sample Mean: 100 Sample Size: 50 σ: 15 Confidence Level: 95% Result: (95.84, 104.16) Type: T-Interval (σ unknown) Sample Mean: 100 Sample Size: 30 s: 12 Confidence Level: 95% Result: (95.47, 104.53) Type: Proportion Interval Sample Proportion: 0.6 Sample Size: 200 Confidence Level: 95% Result: (0.53, 0.67)