Apple selling an estimated $372,000 in iPad apps daily

Vimov, the developer of Weather HD for iPad, has published an estimate of iPad App Store sales based on the volumes of its own top ten app, concluding that Apple is currently selling over $372,000 in iPad apps per day and will likely hit $1 billion in annual sales within two years.

The company's $0.99 Weather HD title was among the first iPad-specific apps available in iTunes. It managed to sell nearly 2,000 copies before iPad even became available, placing fourth in iTunes' Top Selling list behind Apple's own Pages, Numbers and Keynote.

Vimov reported that after the iPad launch, sales of its title hit 3,500 units in one day before falling down into the top twenty apps and then rebounding to the #3 spot.

"This high-start, dive, and then jump," the company said, "while surely affected our sales, gave us the ability to see how sales were at various spots in the App Store’s charts, and with a bit of maths, and by correlating Weather HD’s sales and ranks, to the ranks of other applications, and mixing in the numbers from Apple’s Top Grossing list, we were able to have a good estimate on basically how much money is flowing in the App Store!"

The company estimates that the top 1,000 iPad apps were earning a total of more than $372,000 per day as of the middle of April. Without figuring in new growth in installed base of iPad users, Vimov calculated an annual market worth $136 million, or more than $272 million once international users begin participating in the iPad launch.

When Apple launched the App Store in 2008, it reported that users downloaded ten million apps within the first three days. It went on to hit a billion app milestone in April 2009 just three months short of its first year anniversary. It then hit the 2 billion mark in September and 3 billion in January of 2010. It is likely close to hitting four billion this month.

Vimov suggests iPad apps could hit a billion dollars in in sales per year within two years. Separating iPad app sales from iPhone apps is somewhat difficult, as many apps are begin packaged as Universal Binaries that can work on both platforms, supplying unique, optimized interfaces for each. For users of both iPhone and iPads, upgrades of such apps won't count as either downloads or new sales, because Apple does not count app updates as a new app download.