Inflation numbers are due out today. I'll be interested to see what the press and the experts they consult with have to say about inflation. Think they'll point a finger at the Fed, and try to make it Ben's problem after all?

While we're awaiting the latest consumer price index numbers, here's an interesting topic to ponder: What sort of retirement nest egg might you need to:

• Generate enough retirement income to live at your current standard of living
• Continue to generate income at the same level, net of inflation, for as long as you live

You might not know it, but there is such an investment. One with virtually no volatility and with built-in inflation protection. This investment is at the far end of the risk scale, where risk is virtually eliminated. And as you might guess, just like anything else in this world, you pay for that privilege.

The most conservative approach I know of would entail owning inflation protected treasuries. If you invested 100% of your portfolio in these securities you would be assured a stable and protected income stream for as long as you live. Sweet deal, eh? It really is. But as I mentioned before, it comes at a price.

The price you'll pay to implement this particular retirement strategy is in the lower return on inflation protected treasuries. What this means is you'll need a proportionally larger retirement nest egg to replace a given amount of income.

To replace a $50,000 per year stream of income you might need $2.5 Million or more in these inflation protected treasuries. Probably more, but let's take the easy way out and leave that nasty health care inflation business out of the mix for this discussion. Think you'll need $100k per year to live out your days comfortably? Make that a cool $5 Million you'll need to have socked away.

The general rule of thumb is: You'll need at least fifty times your desired income stream in retirement savings at the time you retire if you want to live a risk-free inflation-adjusted retirement. If you're really risk averse, it's an achievable goal. You have two routes to get there:

1. Save and invest until your retirement portfolio equals 50 times your desired annual income in retirement, or
2. Retire and settle for one-fiftieth of your retirement nest egg as your annual income

Personally, option #2 doesn't look very attractive. That leaves option #1; and as I see it, the only way to amass such a retirement fortune is to take on some risk by investing in securities other than inflation protected treasuries.

And there's the rub. If investing in stocks and other securities got you to a decent sized retirement portfolio in the first place, why change that strategy after you retire?