Mary Robinette Kowal (who seems like a nice person but I know so little about her that she could be a Nazi eugenics researcher and I’d have no idea) posted a Debut Author Lesson that includes this:

I just got an email from my editor that Shades of Milk and Honey is going into its 7th printing.

Seventh.

Between all the US editions so far, we’ve netted 23,793 copies. That’s not counting the UK or foreign language editions.

Seven printings, but under 24K copies. For comparison, Child of Fire sold over 29k copies over the same length of time plus six months. Again, that would be lower than Pat “Maybe I’ll help Nathan Fillion buy the rights to FIREFLY” Rothfuss’s new book sells in a week, but more than many other authors might sell.

Also, we’re not talking identical formats. Ms. Kowal’s novel came out in hardback first, and those editions are more lucrative than mass market paperback. And maybe her sales numbers don’t include ebooks (my paper ed. sales numbers are ~17K). She doesn’t say and I’m not going to ask.

Why?

Because as she says, it doesn’t matter. You can’t really compare the sales figures, because they’re in different genres, different formats, with different expectations. There are probably a lot of UF books that would be considered a success at 29K ebook & mmpb sales, but Del Rey really invested in the CoF, the sequels sold significantly worse than the first, and Del Rey had high expectations.

So congratulations to all writers who are succeeding by their own standards, and supportive fistbumps to all those writers who haven’t succeeded but keep trying.