Apple Inc. (Nasdaq: AAPL) plans to debut a smaller, cheaper iPad by year-end, two people with knowledge of the plans said, to help maintain dominance of the tablet market as Google Inc. (Nasdaq: AAPL) and Microsoft Corp. (Nasdaq: MSFT) prepare competing handheld devices.

The new model will have a screen that’s 7 inches to 8 inches diagonally, less than the current 9.7-inch version, said the people, who asked not to be identified because Apple hasn’t made its plans public. The product, which Apple may announce by October, won’t have the high-definition screen featured on the iPad that was released in March, one of the people said.

A smaller, less expensive iPad could undercut the ambitions of Google, Microsoft and Inc. to gain traction in the advancing tablet market, said Shaw Wu, an analyst at Sterne Agee & Leach Inc. The new device will probably have a price closer to Google’s Nexus 7 tablet and Amazon’s Kindle Fire, both of which have 7-inch screens and cost $199.

“It would be the competitors’ worst nightmare,” Wu said in an interview. “The ball is in Apple’s court.”

Trudy Muller, a spokeswoman for Cupertino, California-based Apple, declined to comment yesterday.

Since the iPad went on sale in April 2010, Apple has dominated the tablet market, which is predicted by DisplaySearch to reach $66.4 billion this year. Apple has 61 percent of the market, according to Gartner Inc.

Apple’s rivals are eager to gain a toehold. Google said on June 27 that it will sell a tablet-style device called the Nexus 7. Earlier in the month, Microsoft announced a tablet called Surface that will have a similar screen size as the current iPad. Amazon’s Kindle Fire was released last year.

Google Strategy

The entrants’ best chance of success has been to focus on markets where Apple had no toehold, said Jan Dawson, an analyst at Ovum Ltd. The Surface comes in two models that are most likely to appeal to buyers who want to continue using Microsoft’s Windows software, Dawson said. While Microsoft has not disclosed pricing or timing for either, the higher-end version will probably be pricier than the iPad and targeted more at an emerging class of laptop PCs called Ultrabooks, he said. The latest iPad ranges in price from $499 to $829.

Google’s Nexus 7 could stack up well against Amazon’s Kindle Fire, which went on sale in November. The Nexus 7, manufactured by Asustek Computer Inc., has a faster processor and better battery life than the Kindle Fire, as well as a front-facing camera.

Still, competing with a lower-priced iPad will be more challenging, Wu said. Apple benefits from having more than 225,000 apps that have been tailored specifically for the current iPad.

Apple Retail

The company also boasts more than 360 retail stores where the device can be purchased and tested by consumers. Google said the Nexus 7 will be available only from its online store, while Microsoft will sell its tablets online and at its smaller chain of 20 stores.

Apple has considered introducing a smaller tablet since the original iPad was released, one person said. That approach has worked for Apple’s iPod, which is the world’s top music player and comes in various sizes and colors.

Yet Apple co-founder Steve Jobs spoke skeptically of smaller tablets before his death in October. He said in 2010 that the iPad’s current size was the minimum required to ensure a good user-experience and enable attractive software applications.

The screen of the small model will have the same number of pixels as those in the iPad before it was upgraded to the so- called Retina Display earlier this year, one person said.

Fatter Margins

Apple also may be at an advantage profit-wise. The gross margin on the latest iPad is about 37 percent, according to Wu. Apple could earn a similar profit on a smaller iPad because it will probably use the cheaper screen, Wu said. Apple can also charge more for the device without sacrificing sales, he said.

“This isn’t like the old days, when it cost thousands of dollars more to buy an Apple product,” Wu said. “Fifty or a hundred bucks wouldn’t be enough to make someone switch.”

Amazon, by contrast, loses money on every Kindle Fire it sells, with the aim of profiting from sales of books and other digital media. At the $199 price of the Nexus 7, Google’s plan should be to break even on the hardware, in exchange for the opportunity to win advertising and related revenue, said Michael Gartenberg, an analyst at Gartner Inc.

Apple’s plans to release a smaller sized iPad were reported previously in blogs, including DigiTimes.

Microsoft’s Stakes

The stakes are high for Microsoft and Google to succeed at hardware sales. Both companies have risked alienating long-time hardware partners, such as Samsung Electronics Co., by selling their own tablets, Gartenberg said.

“How does Samsung make money in tablets, when Google is partnering with Asus to make a product that makes no money?” he asked.

A failure to gain traction with the Nexus 7 and Surface, respectively, might also undermine the credibility of Google’s Android strategy and of Microsoft’s introduction of the next version of the Windows operating system, Wu said. If Google and Microsoft can’t make a must-have product around their own software, consumers may be harder to convince that hardware manufacturers could do it, he said.

“They’re really sticking their necks out this time, putting their own brands on this front and center,” Wu said.