Alright. So, for all of the up and coming rappers out there who may be wondering how to write a 16-bar verse, here is how you do it.
For the most part when you write a line across the page, when you write a line across the page, more often than not, according to how big you write, most rappers, I've done this many years, most rappers, when they write a line across the page that usually equates to one bar.
That equates to one bar. So, if you said "I'm the illest rapper alive. Watch me do my thing." That's usually one bar. So, 16 lines down the paper will equal to 16 bars. And to double check, what you usually do is you find the section of the song, of an instrumental, that is the same amount of time as a regular 16 bar verse. And once you finish writing your 16 lines, you measure it by rhyming, or rapping, your verse along that same time period. If it goes over than you know it's over. But, more often than not, 16 lines on a paper will lead you into 16-bar verses.