NEW YORK (CNNMoney) -- How much does Facebook value its users? In strictly monetary terms, about as much as a bag of chips.
Facebook is raking in a little over $1 billion in sales every three months. That sounds like a big number, but with more than 900 million active users, it means each Facebook user is bringing in just $1.21 a quarter.
It's an astoundingly low number compared to other companies that report average revenue per user, or ARPU. The metric is usually used by service providers and communications companies, which typically collect hundreds of dollars per quarter from each customer through subscription fees and other charges.
For instance, Verizon (VZ, Fortune 500) FiOS customers pay an average of $444 for three months of service, and Time Warner Cable (TWC, Fortune 500) receives $348 from its users over that span. AT&T (T, Fortune 500) brings in $193 for three months of contracted mobile service, and customers of Sprint's (S, Fortune 500) prepaid Boost Mobile and Virgin Mobile brands pay the company $80.46 every three months.
Those companies have very different business models than Facebook, so their ARPUs aren't anything close to an apples-to-apples.
That's what makes Facebook's decision to include ARPU in its quarterly financial reports so surprising. For service providers, ARPU is a valuable metric that helps the companies and their investors understand how much customers are paying for their services each month.
Facebook (FB) customers don't pay the social network directly -- they upload their personal information, which Facebook uses to attract advertisers. (For a look at how Facebook profits from your data, check out "How you help Facebook make billions.")
Averaging each Facebook user isn't remotely the same as averaging phone plans or cable bills. Different advertisements appear for each Facebook user, and the cost and quality of ads varies tremendously in different regions.
For instance, Facebook's ARPU in the United States and Canada is almost twice its global average, coming in at $2.23 per quarter. Facebook's fastest user growth is coming from developing countries, where the company says the ad market brings in significantly lower sales. Its quarterly ARPU is just 61 cents in those regions.
Also, some users log on once a month and see just a few ad impressions. Others spend virtually their entire day on Facebook and are eyeing hundreds or thousands of ads. Some use the company's ad-filled website, while others stick to the ad-free mobile app.
All of that makes the worldwide "average" a difficult statistic to make heads or tails of.
That's why it's extremely rare for Internet companies to break out ARPU. Facebook is probably calling out ARPU in an attempt to draw attention to its growing non-advertising business like in-app payments, but since more than 85% of the company's sales are still made up of advertising, the number remains kind of silly.
Meanwhile -- since Facebook did us the favor of starting the conversation -- we took the liberty of seeing how Facebook's ARPU stacks up against other Internet companies.
To calculate Facebook's competitors' ARPU, we divided the company's first-quarter revenue by the total number of unique visitors for March 2012 as reported by either the companies themselves or by comScore (SCOR). It's a fast-and-loose number, but it tells an interesting story.
Both Twitter and Microsoft (MSFT, Fortune 500) make even less per user on their Internet properties than Facebook.
Twitter is generating 74 cents per user per quarter, according to a revenue estimate from eMarketer. The six-year-old site struggled for years to figure out a way to monetize its service, but it has recently been making headway in the advertising business.
Meanwhile, Microsoft's online business is losing upwards of $1 billion per quarter as the company spends lavishly to grow MSN and Bing's market share. Currently, its quarterly ARPU stands at 81 cents.
Social network LinkedIn's (LNKD) ARPU isn't much higher than Facebook's, coming in at $1.76 per quarter.
Top search engines like Baidu and Google seem to offer a better business model. China's Baidu brings in $2.54 per user per quarter, and Google makes $7.14.
"It's a different type of advertising," said Debbie Williamson, an analyst at eMarketer. "For Google, advertising is related to what you're searching for. Facebook has built a whole new form of advertising based on targeting to users' expressed interests, as well as information about themselves and what their friends do."
The key for Facebook's ARPU growth, Williamson said, is for Facebook to prove that its new style of ads work better than search-driven ads like Google's. Some advertisers aren't buying it. In one ill-timed blow, General Motors (GM, Fortune 500) said this week that it will stop spending money on Facebook ads.
"The secret for Facebook will be better targeting and more proof that social cues make targeting advertising easier," Williamson said. "Facebook has to show that social causes users to have more affinity for and engagement with ads." 
