When I was putting together my ER plan back in 2007-08, one thing I did was to try to predict what my SS benefit would be after I stopped working near the end of 2008. I went into the SSA website and after looking up the benefit calculation, I created a spreadsheet which mimicked it. This included a bunch of zero wage earning years because I had only 26 years with nonzero wage earnings.
However, I wasn't sure I did it right so I wanted a way to check my work. I found the ANYPIA program and downloaded it. I had some trouble getting it to work at the time but I knew I would try again at some point. A few years later, after I had become a member here and in Bogleheads, I had gotten some advice about how I could get it to work right (I don't recall what it was, but it was something easy or stupid, or I just got inspired enough to give it another try), I got the ANYPIA program to work.
ANYPIA's estimated monthly benefit was only a dollar or so away from my spreadsheet, so I knew I had my spreadsheet right. With no wage earnings in the calculation since 2008, my SS benefit was basically frozen. Every few years or so, I would go to the SSA website and cut and paste a set of updated wage index factors which would change the estimated monthly benefit a few dollars tops.