Confidence interval of a SD

It is straightforward to calculate the standard deviation from a bunch of values. But how accurate is the standard deviation? Just by chance you may have happened to obtain data that are closely bunched together, making the SD low. Or you may have happened to obtain data that are far more scattered than the overall population, making the SD high.If you assume that your data are randomly sampled from a population that follows a Gaussian distribution, This calculator can compute a 95% confidence interval for the standard deviation.