To determine the sample size for the Central Limit Theorem (CLT) to apply, it is essential to consider the distribution of the data. A common rule of thumb suggests that a sample size of around 30 is generally sufficient for the distribution of the sample mean to approximate normality. However, this is not a strict calculation and can vary based on the underlying distribution characteristics. The Berry-Esseen theorem can provide additional insights into how quickly the distribution of the sample mean converges to normality. Understanding these principles is crucial for accurate statistical analysis.