I recently got a rare telephone call from someone at my brokerage, checking up on its "self-directed investors" -- that is, the customers who choose not to pay hefty commissions for financial advice. "How's that working out for you?" he asked, like a friendly financial Dr. Phil.

We should all be able to confidently answer that question most of the time, without glancing at the latest news of market turbulence or prognostications of financial catastrophe. You shouldn't even have to be a math whiz, or harbor a burning love of spreadsheets.

The right question
Just reach into your magical filing cabinet and pull out your most recent report of portfolio returns. What? You don't have a magic wand, or the patience to spend your weekend compiling financial reports? Me neither.

That doesn't get us off the hook, I'm afraid. It's also, unfortunately, not enough just to look at the bottom line. If you're not losing money, it's very tempting to declare victory and move on to some other pressing project, like rearranging your sock drawer by color and texture.

But ignore the chaos overtaking your hosiery, and ask yourself: How do your returns compare to the average performance of the stock market? Consider this a friendly reminder of one of The Motley Fool's investing basics: "Any money that you have to invest for five years or longer should not underperform the market over that five-year period."

Do the math
To find out how you're doing, you need to compare your returns to some measure of the market's average performance. You have a few options to get an idea of the big picture. There's the S&P 500, a measure of 500 of the country's largest companies. Take a look at the box on The Motley Fool homepage, and you'll see all of our investment picks measured against this benchmark. There's also the broader market, which includes thousands of smaller companies, tracked by index investments like Vanguard's Total Stock Market ETF (AMEX:VTI) or the SPDR Wilshire Total Market ETF (AMEX:TMW).

If you want to get a more detailed look at how you're doing, compare specific investments to more specific indexes. For instance, say you own shares in the Dodge & Cox International Stock (DODFX) mutual fund, a Champion Funds pick. You're probably not interested in how it compares to the performance of U.S. large caps like Cisco (NASDAQ:CSCO) and General Electric (NYSE:GE), because you bought the fund for international exposure. Instead, you want to compare it to foreign stocks like Vodafone (NYSE:VOD) and GlaxoSmithKline (NYSE:GSK), which are included in the handy MSCI EAFE Index.

There's an index for everything these days, and virtually everything in your investment portfolio can be sized up against a measure of the market's average performance.

Cheat on your homework
That's an easy concept to grasp, but a difficult one to put into action, especially if numbers make you break out in hives. Fortunately, we live in the modern age, and we can cheat a little bit. You've got a million electronic tools at your fingertips.

For example, check your financial statements to see whether your brokers report your personal rate of return. Many do, and that convenience can save you a lot of time. If not, find a way to painlessly track your returns. Financial software like Quicken and Microsoft Money will download the numbers, then slice them and dice them.

If you don't want to fork over the money to buy financial software, check out some of the free portfolio tracking devices, such as those offered by Google and Yahoo!. For mutual fund owners, Yahoo!'s financial statistics compare mutual fund returns against sector-specific indexes. They've done the work for you.

To be able to answer the random phone calls from your broker with confidence, check in every once in a while to make sure you're still on track. If you want to delve a little deeper, keep reading:

Too busy to fiddle with financial flow charts? Check out the Motley Fool Green Light action plan for investing when you're short on time. It's just one nifty feature offered by this great service to help you meet your money goals. It's also free for you to peruse in your spare time for 30 days.

Fool contributor Mary Dalrymple does not own stock in any company mentioned in this article. She welcomes your feedback. Dodge & Cox International Stock is a Champion Funds pick. Yahoo! is a Stock Advisor selection. The Motley Fool has a high-performing disclosure policy.