How much is enough?
Just like the accumulation phase we have lots of variables. Let's consider how they affect your retirement income. Typically we have an income budget. Besides spending needs what can affect it?
Another way to look at this is Purchasing Power. If inflation is 3% and your income never increases, Your income will only purchase 1/2 of the things it does today.
How long will one or the other member of a couple live? Life expectancy has been increasing and may continue to do so. When you plan your income should you consider having the income last to 90 years old or even 100?
Safe Withdrawal Rates
This concept is one that takes into account your withdrawal amount, the rate of return, taxes and inflationary raises. It examines the length of time that your money will last if you take out 5% per year versus any other withdrawal rate and calculates how long it will take to deplete the investment entirely.
Maintaining a plan and reviewing your progress on a periodic basis with your financial advisor will help you stay on track in retirement.