Sample size is a critical factor in survey research and academic studies for ensuring reliable results. Larger samples reduce error but increase cost.
This calculator uses standard formulas: n = Z²×p×(1-p) / e² (infinite population) or n = (N×Z²×p×(1-p)) / (e²×(N-1) + Z²×p×(1-p)) (finite population correction).
Z-values for confidence levels: 99%=2.576, 95%=1.96, 90%=1.645.