Inflation is one of the key factors you will need to consider when planning for retirement. Not only will the cost of living rise while you're accumulating assets for retirement, but it will continue to rise during your retirement, which could last 25 years or longer. This, combined with the fact that you will not likely earn a paycheck during retirement, is the main reason your portfolio needs to maintain at least some growth potential for the duration of your retirement.
Consider this: If inflation runs at 3% (which is approximately its long-term average, as measured by the Consumer Price Index), the purchasing power of a given sum of money would be cut in half in 23 years. If it averages 4%, your purchasing power would be cut in half in 18 years.
A simple example illustrates the impact of inflation on retirement income. Assuming a consistent annual inflation rate of 3%, if $50,000 satisfies your retirement income needs this year, you'll need $51,500 of income next year to meet the same income needs. In 10 years, you'll need about $67,195 to equal the purchasing power of $50,000 this year. And in 25 years, you'd need nearly $105,000 just to maintain that purchasing power!1
Keep in mind that even a 3% long-term average inflation rate conceals periods of skyrocketing prices, such as in the late 1970s and early 80s, when inflation reached double digits. Although consumer prices have been relatively stable in more recent decades, there's always the chance that unexpected shocks could cause prices to spike again.
So how do you strive for the returns you'll need to outpace inflation by a wide enough margin both before and during retirement? The key is to consider investing at least some of your portfolio in growth-oriented investments, such as stocks.2
1This hypothetical example of mathematical principles is used for illustrative purposes only and does not represent the performance of any specific investment. Note that these figures exclude the effects of taxes, fees, expenses, and investment returns in general.
2All investing involves risk, including the possible loss of principal, and there is no guarantee that any investment strategy will be successful.