Facebook is booming in Turkey and Indonesia. YouTube’s audience has nearly doubled in India and Brazil.

That may seem like good news. But it is also a major reason these and other Web companies with big global audiences and renowned brands struggle to turn even a tiny profit.

Call it the International Paradox.

Web companies that rely on advertising are enjoying some of their most vibrant growth in developing countries. But those are also the same places where it can be the most expensive to operate, since Web companies often need more servers to make content available to parts of the world with limited bandwidth. And in those countries, online display advertising is least likely to translate into results.

This intractable contradiction has become a serious drag on the bottom lines of photo-sharing sites, social networks and video distributors like YouTube. It is also threatening the fervent idealism of Internet entrepreneurs, who hoped to unite the world in a single online village but are increasingly finding that the economics of that vision just do not work.

Last year, Veoh, a video-sharing site operated from San Diego, decided to block its service from users in Africa, Asia, Latin America and Eastern Europe, citing the dim prospects of making money and the high cost of delivering video there.

“I believe in free, open communications,” Dmitry Shapiro, the company’s chief executive, said. “But these people are so hungry for this content. They sit and they watch and watch and watch. The problem is they are eating up bandwidth, and it’s very difficult to derive revenue from it.”

Internet start-ups that came of age during the Web 2.0 era, roughly from 2004 to the beginning of the recession at the end of 2007, generally subscribed to a widely accepted blueprint: build huge global audiences with a free service, and let advertising pay the bills.

But many of them ran smack into global economic reality. There may be 1.6 billion people in the world with Internet access, but fewer than half of them have incomes high enough to interest major advertisers.

“It’s a problem every Internet company has,” said Michelangelo Volpi, chief executive of Joost, a video site with half its audience outside the United States.

“Whenever you have a lot of user-generated material, your bandwidth gets utilized in Asia, the Middle East, Latin America, where bandwidth is expensive and ad rates are ridiculously low,” Mr. Volpi said. If Web companies “really want to make money, they would shut off all those countries.”

Few Internet companies have taken that drastic step, but many are exploring other ways to increase revenue or cut costs in developing countries.

MySpace — the News Corporation’s social network with 130 million members, about 45 percent of them overseas — is testing a feature for countries with slower Internet connections called Profile Lite. It is a stripped-down version of the site that is less expensive to display because it requires less bandwidth.

MySpace says it may make Profile Light the primary version for its members in India, where it has 760,000 users, although people there could click on a link to switch to the richer version of the site.

Perhaps no company is more in the grip of the international paradox than YouTube, which a Credit Suisse analyst, Spencer Wang, recently estimated could lose $470 million in 2009, in part because of the high cost of delivering billions of videos each month. Google, which owns YouTube, disputed the analysis but offered no details on the site’s financial situation.

Tom Pickett, director of online sales and operations at YouTube, says the company still hews to its vision of bringing online video to the entire globe. In the last two years, it has pushed to create local versions of its site in countries like India, Brazil and Poland.

But Mr. Pickett also says that YouTube has slowed the creation of new international hubs and shifted its focus to making money. He says that does not rule out restricting bandwidth in certain countries as a way to control costs — essentially making YouTube a slower, lower-quality viewing experience in the developing world.

“We may choose to set a limit to how much we are willing to pay in bandwidth cost,” Mr. Pickett said. In some countries, he said, “there may be particular peak times where instead of high definition, we might decrease the resolution.”

The Facebook social network is also considering lowering the quality of videos and photographs delivered to some regions in an effort to reduce expenses.

“We can decide, either on a country by country or user by user basis, to engineer the quality of the service for that cohort of users,” said Jonathan Heiliger, the executive who oversees Facebook’s computing infrastructure.

Facebook is in a particularly difficult predicament. Seventy percent of its 200 million members live outside the United States, many in regions that do not contribute much to Facebook’s bottom line. At the same time, the company faces the expensive prospect of storing 850 million photos and eight million videos uploaded to the site each month.

Facebook, which says it favors membership growth over profitability for now, is trying to increase revenue overseas by hiring advertising sales staff in countries like Britain, Australia and France.

In other parts of the world, Microsoft serves ads on the site and Facebook offers self-service tools to advertisers. But those ads are far less lucrative than the ones Facebook itself sells in the United States and Western Europe.

As a result, speculation has swirled about Facebook’s finances. Industry analysts wonder aloud how fast the company is losing money and whether it needs to solicit another round of investment.

Facebook said last month that it was on track to become profitable next year. But as it did, Gideon Yu, Facebook’s experienced chief financial officer, left the company. Three people familiar with the internal maneuverings at Facebook said Mr. Yu objected to such a rosy projection as the company was struggling to finance its expensive global growth.

Web entrepreneurs like Mr. Shapiro of Veoh, still struggling with his decision to restrict his site from much of the world, might have to find a way to soothe their battered consciences.

“The part of me that wants to change the world says, ‘This is unfair, it shouldn’t be like this,’ ” Mr. Shapiro said. “On the other hand, from the business side of things, serving videos to the entire world is just not supportable at this time.”