This guest post comes from Matt Haddad, who is taking the Entertainment Law and Web 2.0 minterm course at Southwestern Law School:

Musicians often are more adept at composing and performing tunes than calculating and computing royalties. Hollywood, for this reason, is filled with tales of young artists who are thrilled to win a contract and envision a future filled with riches, only to find later that they’re not earning enough money to pay their rent; they naïvely have relied on others’ word about the soundness of their contracts, disregarding the nitty-gritty details of production costs, agent and manager fees and touring and other costs that get tallied on their tab.  And while music accounting has been as complex as calculating rocket trajectories, there’s now, yes, a new app (and others) to assist: the Moses Avalon Royalty Calculator. Entertainment talent — and lawyers, too — might want to put away their scratch pads, slide rules and pencils and check this out:

Moses Avalon is the pseudonymn of a music industry activist who worked for years as a record producer and recording engineer.  He is the author of Million Dollar Mistakes and Confessions of A Record Producer.  You can read his blog, Moses Supposeshere and check out his website, www.mosesavalon.com or join Confessions Workshop Online to see the wide-angled lens approach he takes to the entertainment business.

 You also may download his free app to your iPhone here. For 99 cents, you may upgrade to an app without advertisements; for $4.99, there’s the “pro” app. Whichever app you tap,  follow the basic instructions and maneuver through the maze of possibilities for royalty deals.  You must enter accurate numbers to get a fair representation of royalties earned.  The app is not a substitute for your specific deal information but rather a method for clear presentation of industry norms and the figures you enter.
There are similar products, such as the Royalty Calculator by Financial Softworks, LLC, released in November, 2011, for Android users here  and for Apple users here.  Also, the Harry Fox Agency offers a free mechanical royalty calculator here.
As for the the Moses Avalon Royalty Calculator, it seems, at least in a recent cursory test, to be a deluxe, all-inclusive tool to demystify how royalties  are computed.
While the apps offer a 21st Century tool, caveat emptor, of course, tune-smiths and other legal talent: Test these products for yourself for fun or business but remember that a lawyer and real-life, sound legal counsel’s a key before signing any binding documents, such as contracts.