The official stance from meta.stackexchange.com (the meta of all meta's)  is a [maximum of 30 000 characters](https://meta.stackexchange.com/questions/176445/knowing-your-limits-what-is-the-maximum-length-of-a-question-title-post-image) but there seem to be answers containing code that are longer than that, so **my guesstimate** is 30 000 characters of text and another 30 000 of code, but I'm too lazy to actually put that guesstimate to the test.