What kind of average royalties do authors usually receive from publishing companies?

This varies from company to company and author to author, but the industry does have some standards. Generally a hardback release is paid ten percent of the sale price on the first ten thousand volumes sold, less any advance paid out. Over ten thousand copies bring in fifteen percent of the sale price.

Paperback sales are much more complicated due to the returns system in place. Standard deal gives the author five percent of the sale price to a certain sales point, usually one hundred thousand copies, and seven percent of the sale price there after, but the publisher witholds a percentage of this against anticipated returns, and the formula for figuring this is rather arcane.

Other things effect actual royalties--when a book is heavily discounted, its sale price can be far below its cover price. The percentages are based on this price, not the one printed on the book. Electronic sales do not yet have a widely accepted standard.What kind of average royalties do authors usually receive from publishing companies?
It's different for every author/book, but generally speaking authors receive 10-15% for hardbacks and 6-8% for paperbacks.What kind of average royalties do authors usually receive from publishing companies?
Depends on the publishing companies, but it usually confined to single and lower double digits. Also, you may get an advance, but you have to earn it.