Americans say they need help, but guess what? Nobody can answer these questions for you.
There is only one significant variable to worry about. Health care expenses, especially if you have employer- funded benefits while working, your costs will increase significantly. Check out Medicare Part B, Part D and Medigap policies.
Otherwise, assume your spending level will remain the same (even if spending is on different things) unless you go from a mortgage to no debt.
However, you should ask yourself if you are planning to or willing to change your lifestyle, including relocation.
So, if you need $40,000 in addition to Social Security, you need a nest egg of about $1,000,000. It could be a bit less if you use tax free investments such a Roth accounts.