What lump sum at retirement will provide an income stream at retirement to enable you tomaintain your desired standard of living assuming you live to your life expectancy

To answer this question, you need to consider several factors:

1. Desired Annual Income: Determine how much money you will need each year during retirement to maintain your desired standard of living. This amount should include all your estimated expenses such as housing, food, healthcare, travel, and other personal expenses.

2. Life Expectancy: Estimate how long you expect to live after retirement. This is typically based on average life expectancy rates, but personal health and family history can also be factors.

3. Rate of Return: Estimate the annual rate of return on your retirement savings. This will depend on how you invest your money.

4. Inflation: Consider the impact of inflation on your retirement savings. The value of money decreases over time due to inflation, so you need to factor this into your calculations.

Once you have these figures, you can use a retirement calculator to determine the lump sum you will need at retirement. The formula used by these calculators is typically something like this:

Lump Sum = Desired Annual Income / [(1 - (1 + Rate of Return)^-Life Expectancy) / Rate of Return]

This formula calculates the present value of an annuity, which is the lump sum needed to generate a certain income stream for a certain number of years, given a certain rate of return.

Remember, this is a rough estimate. It's always a good idea to consult with a financial advisor to get a more accurate assessment of your retirement needs.