The lower and upper fence are calculated in order to identify the outliers. The data that lies outside the upper and lower limits are called as the outliers. Here is the lower and upper fence formula for calculating the upper and lower limits on your own. It is necessary to know the first, second and interquartile to find the upper and lower fence. Just substitute the first, second and interquartile values in the formula and do the operations as guided by the formula to get the result.
According to the lower and upper limit formula, upper fence formula needs the first quartile as the input but whereas lower fence formula needs the third quartile as the input. On the whole, both the formulas require interquartile range value as a common input.