Sample Size Calculator
Enter your population size, confidence level, and margin of error to calculate how many responses you need for statistically valid survey results.
Survey Size Calculator
Calculate the minimum number of survey responses needed for statistically valid results.
Total number of people you could survey
How certain you want to be (95% is standard)
Acceptable error range (5% is standard)
Quick Reference
| Population | ±3% | ±5% | ±10% |
|---|---|---|---|
| 100 | 92 | 80 | 49 |
| 500 | 341 | 217 | 81 |
| 1,000 | 516 | 278 | 88 |
| 5,000 | 879 | 357 | 94 |
| 10,000 | 964 | 370 | 95 |
| 50,000 | 1,045 | 381 | 96 |
| 100,000+ | 1,067 | 383 | 96 |
These values assume: 95% confidence, p = 0.5, and finite population adjustment.
How Many People to Invite?
The calculator gives you:
- Minimum sample size (responses required)
- Adjusted send size (based on expected response rates)
Typical Response Rates
| Survey Type | Response Rate |
|---|---|
| In-app | 20-40% |
| Email customers | 10-30% |
| Employees | 30-50% |
| Transactional | 15-25% |
| NPS | 10-20% |
Invite formula: People to invite = Required responses ÷ Expected response rate
Example: Need 400 responses, expect 20% → invite 2,000 people.
Next Steps
For the full explanation of sample size statistics, formulas, and best practices, see Understanding Survey Sample Size.
Once you know your required sample size, create and launch your survey with our templates.