Confidence Interval Proportion Calculator
Confidence interval for a sample proportion.
Work It Out And Get Clear Answers
Confidence interval for a sample proportion.
Confidence Interval Proportion Estimator
Enter your numbers below for an instant estimate.
How It Works
Key concepts behind this calculator
Enter Values
Fill in each field with your own numbers.
Calculate
Press Calculate to see the result.
Review
Read the breakdown and the explanation.
Adjust
Change values to compare scenarios.
Confidence Interval Proportion Quick Guide
Typical values for reference.
| Sample proportion (0 to 1) | Sample size | Z-score (1.96 for 95%) | Margin of error |
|---|---|---|---|
| 0.4 | 200 | 1.96 | 6.79% |
| 0.2 | 200 | 1.96 | 5.54% |
| 0.8 | 200 | 1.96 | 5.54% |
| 0.4 | 100 | 1.96 | 9.6% |
| 0.4 | 400 | 1.96 | 4.8% |
| Rule of thumb: check your inputs, use the result as a guide and round sensibly. | |||
Confidence Interval Proportion FAQ
Answers to common questions about this calculator.
CI = p ± z × √(p(1−p) ÷ n).
It uses the default inputs shown and the formula described above. Change any value and press Calculate to see how the result moves.
It is an estimate based on the inputs you enter. Check real quotes, labels, product data or official guidance for important decisions.
Yes. Replace each input with your own figures and press Calculate to update the result.