Congratulations @Suzzzzzz59 for having some foresight for retirement which could be right around the corner. I know of no formula because I'm not sure I'd trust a formula for something so crucial to the rest of your life. Do you have thoughts of speaking with a financial advisor? It can be so complicated and some of the timing is unpredictable since most of us have no idea of our lifespan. Even with guaranteed income, some of it may be taxable. If you become mortgage-free, there are still property taxes and homeowner's insurance, maintenance and repairs to consider with ownership. A good financial planner can help you form a timeline and path to a stress-free retirement.