You think this would be an easy question…but it's not. Let me ask you:
What age are fairytales for? What age are Grimm's fairytales for? What age is Ursula LeGuin's A Wizard of Earthsea for?
When I was young, books were categorized much differently than they are now. Fantasy was closer to its fairytale roots, so many books were intended for adults, but written in a fairytale style.
This made them fun for kids to read.
But they weren't written for kids. The problem with saying, "It's for kids" is that in our current culture, that is often read as "not for adults."
A Wizard of Earthsea was one of my favorite books when I was between 12 and 15. If you haven't heard of it, it is the book that invented the idea of wizard schools. I love Harry Potter and Hogwarts, but in my heart Roke will always be THE wizard school, because I had fallen in love with it decades before Hogwarts came along. (Though Hogwarts for high school and Roke for college would be a great combination!)
Nowadays, I sometimes see A Wizard of Earthsea in the YA section. But it wasn't written for teens. It was written for adults. It just happened to have a young character.
On top of that, there is the fact that when YA got started, it was actually meant for Young Adults. It was publishing gimmick to take some good but not too difficult adult books and repackage them to attrack the attention of readers in their late teens and early twenties. Readers moving from kids stuff to adult stuff who might like a book that has a young appeal.
Then twelve-year-olds started reading what the older kids were reading. Then, parents started complaining about what was in the YA books, and the current tug of war started–where no one in the industry really knows what a YA book is supposed to be like. (Or at least it was like that ten years ago. Maybe they've settled it by now.)
Back to the Books of Unexpected Enlightenment. Putting aside the very first book, which I did write to a slightly younger level, this series is like these older books. They are written for…readers.
That being said: this series is targeted at older teens. By targeted, I mean that the questions being explored are ones that older teens might be facing or interested in, so they are the group I hold foremost in my mind when I consider how the story is presented. This despite the fact that Rachel the character, happens to be 13.
So, if when you ask "what age are the books for", you mean "are they interesting enough for adults", the answer is definitely yes. Most of my readers at the moment are adults, only because I haven't managed to reach many teens yet. (The teens who have read the series love it.)
But, if what you mean is: How young is the series safe for, that's a very different question.
Rachel herself is 13 in the first five books. In these books I have tried to tone down the more mature elements. A few very disturbing things happen, but I try not to sensationalize them in any way, so they are not dwelled upon.
I have readers who are ten and 12. (I have parents who have read the books to younger kids. But, of course, if you are reading aloud, you can skip over any clear indication of what happened to Valerie Hunt, descriptions of Carthaginian sacrificial rites, and the other more disturbing aspects of the story. )
If you ask me, myself, I would say 12 is a good starting age, but a precocious ten-year-old might do well.
The later books will deal with more mature issues and more disturbing occurrences. They will however remain in the same general mood and flavor with the same moments of brightness and wonder. It’s just that great accomplishments require terrible adversaries, and terrible adversaries are…terrible.
I would put the starting age for those books at 15.
So, short answer? The books are for everyone. They are particularly intended for young people who are actively considering their own ethics, principles, etc. These early books are probably appropriate for 12-year-olds, though some younger readers have enjoyed them.
They are books, for readers.
Hope that helps. I might add that about the same thing—minus the slight change in maturity level as the series continues—could be said about the age level of John’s Tales of Moth and Cobweb series.
Through October 17th, The Unexpected Enlightenment of Rachel Griffin is still FREE
Through October 17th, The Raven, The Elf, and Rachel is 99 cents
Also, there is now an audio version of The Unexpected Enlightenment of Rachel Griffin avaiable on Amazon and Audible.