Here's why Amazon.com (Nasdaq: AMZN) may be cheaper than you think.

In the daily noise machine of CNBC, analyst estimates, and quarterly announcements, investors are inundated with talking heads obsessing over earnings-per-share figures.

Earnings, or net income, is an accounting construction that is the basis for the price-to-earnings ratio, the most popular way of measuring how cheap or expensive a stock is.

But free cash flow -- the amount of cash a company earns on its operations minus what it spends on them -- is another, oftentimes more accurate measure of earnings that can give you an advantage.

How Amazon.com stacks up
If Amazon.com tends to generate more free cash flow than net income, there's a good chance earnings-per-share figures understate its profitability and overstate its price tag. Conversely, if Amazon.com consistently generates less free cash flow than net income, it may be less profitable and more expensive than it appears.

This graph compares Amazon.com's historical net income to free cash flow. (I omitted various gains and charges such as tax deferrals, restructurings, and benefits related to stock options.)

Amznnetincomefcf
Source: Capital IQ, a division of Standard & Poor's, and author's calculations.

As you can see, Amazon.com has a tendency to produce more free cash flow than net income. This means that the standard price-to-earnings multiple investors use to judge companies may overstate its price tag.

There can be a variety of reasons to disregard such a discrepancy; for example, free cash flow can overstate earnings in businesses with volatile working capital needs, or understate earnings in high growth companies that are reinvesting capital in the business.

Alternatively, in cases where free cash flow more accurately measures earnings, such a discrepancy can indicate a company that is more -- or less -- expensive than investors realize.

Let's examine Amazon.com alongside some of its peers for additional context:

Company

Price-to-Earnings Ratio

Adjusted Price-to-Free-Cash-Flow Ratio

Amazon.com 67.8 59.2
Google (Nasdaq: GOOG) 23.2 36.8
eBay (Nasdaq: EBAY) 24.2 37.1
Overstock.com (Nasdaq: OSTK) 30.0 66.4

On a P/E basis, Amazon.com looks pricier than its peers.

Amazon.com's free cash flow multiple is less expensive than its earnings multiple, suggesting that Amazon.com's stock might be somewhat cheaper than many investors realize.

Interested in any of these stocks? You can keep track of them by adding them to My Watchlist:

Ilan Moscovitz owns shares of Google. Google is a Motley Fool Inside Value pick. Google is a Motley Fool Rule Breakers recommendation. Amazon.com and eBay are Motley Fool Stock Advisor selections. The Fool owns shares of Google. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.