 Sample size calculations are essential for health research, but they are often not reported in published studies. This paper explains the importance of sample size calculation and provides guidelines for selecting an appropriate sample size based on the type of study being conducted. The paper also discusses how to select an appropriate sample size given the desired precision, power, confidence level, and effect size. Finally, it emphasizes the importance of having an open and honest discussion between researchers and health practitioners about the appropriateness of the calculated sample size. This article was authored by Allah al-Thabadi.