How much is enough? In my early career I probably had about three months cover at best, and occasionally zero ie no savings at all, and that really didn't change a lot until the last decade of my more gainful period of employment. I never really calculated it much until the mid 90's when I had around 6 years cover ie dead stop no income at all and money would run out in 6 years. This steadily increased to around 13 years by 2000 and to about 30 by 2004 (which is when my income peaked and when our mortgage was finally dead and buried. We now sit in the position of not ever running out and continuous growth.
I never once imagined I would ever be in this position in all my life esp' back in the mid 80's when, although I had a good income even then, mortgage rates were high plus young family etc and I remember having only £10 a month unassigned that we could spend how we wanted.
We are not really wealthy just nice and comfy but I think the big learning lesson for me was when I met someone who really managed his money properly and he inspired me to do the same. I can pinpoint the switch from being spenders to savers (although we are not stingy by any stretch) to the exact moment when I had several conversations with him about how to manage my personal finances better. Bit odd really - for a lot of my career I managed very large budgets and complex financial scenarios but had never applied my expertise to my personal circumstances.
I've used one of these little online calculators in the past but I now use a Excel spreadsheet to plot income/expenditure projections etc. Lovely wife takes the proverbial about my colourful cash flow and savings projection graphs although she does appreciate the comfort factor they provide.
This just plots impact on savings with regular monthly withdrawals but is useful nonetheless:
https://www.calcxml.com/calculators/how-long-will-my-money-last?skn=