stats
Sample Size
Required n for a proportion or mean estimate at a given confidence and margin of error.
Inputs
Estimate Type
Confidence Level
p = 0.5 gives the largest (most conservative) n.
Z* = 1.96 for 95% confidence.
Z* = 1.96 for 95% confidence.
Results
Required Sample Size n—
n at common margins (95% confidence, p = 0.5)
| Margin of Error | Required n |
|---|---|
| ±1% | 9,604 |
| ±2% | 2,401 |
| ±3% | 1,068 |
| ±5% | 385 |
n = ⌈ Z² × p(1−p) / E² ⌉