A sample size calculator helps determine how many observations or responses you need to collect for a survey, experiment, or study to achieve statistically significant results.

Proper sample size ensures your study has enough statistical power to detect meaningful effects or differences. Too small a sample may miss important findings, while too large wastes resources.

Confidence level represents how certain you can be that the population parameter lies within your margin of error. A 95% confidence level means if you repeated the study 100 times, 95 of them would produce similar results.

Margin of error indicates the range within which the true population value is expected to fall. A ±5% margin of error at 95% confidence means that if you surveyed all population members, the results would differ by no more than 5% in 95 out of 100 cases.