The Linsear Write Metric system uses a sample of 100 words to calculate the American level of text understanding. The Flesch-Kincaid classification gives a number that corresponds to the American level, which is usually necessary to understand the text. An automatic readability index also gives an American score corresponding to the degree of readability of the text. It sends the median to Google Analytics as a custom measure and collects reading time as an additional custom measure. If the score exceeds 10, it can also be used to calculate the number of years of training needed to understand the text. To calculate the time of reading text, we use a link of 250 words per minute, read by an average adult. It calculates the average number of letters of a word from the whole text and multiplies it by 100 to get the average number of letters from a sample of 100 words. Typically, these formulas give an estimate that roughly indicates the level of training needed to read a passage of text easily. In this article, I will show you how to create a custom JavaScript variable in Google Tag Manager that creates a utility. The performance of regular expressions decreases with increasing content and, in the case of large text, analysis can make it difficult to load pages.