How can we determine how much income our savings could generate if we purchase an annuity?
Annuity calculation formulas can be found here. http://en.wikipedia.org/wiki/Annuity_(finance_theory). In addition, as suggested in the comments, there are many sites that have calculators. Having said that, a simple financial mechanism that is followed by many is to invest a portion of the fund in regular income instruments, for example Govt. or corporate bonds that pay a regular coupon/interest and some in diversified instruments like gold, stock etc. The exact proportion is dependent on may factors, like mortality, inflation, lifestyle, health care requirements, other expenses. The regular income provides the day to day expenses on a monthly/yearly basis, while the other instruments hedge against inflation and provide growth.