There is a rule in the personal finance community called the 4% rule or safe withdrawl rate (SWR). It basically states that once you are retired you live off 4% of your net worth, which is the safe amount to spend to ensure you don’t run out of money.
The 4% rule is based on the Trinity Study which looked at a portfolio of 50% stocks and 50% bonds to see how likely it was to run out of money over 30 years.
The video above shows how complicated the four percent rule can be and why it is better in my opinion to simply live off your investment income (dividends, rent, interest, etc) as there is no calculation involved and no work. Everything is on autopilot. That being said when living off dividends there is a trade off between income and growth (see The Problem with HVST) and this is where I think the four percent rule can be used as a guide. If your dividend income is more than 4% of your net worth, invest more in growth assets whereas if your dividend income is less than 4% of your net worth, invest in income-producing assets.
I Live Off Dividends 