The following are broad guidelines using information found on the Children’s Book Council Website. Please check with your particular publisher’s specific guidelines before submitting.
Age: The ages for which books are published.
Picture Books: Preschool, 0 - 5; from 500 – 1,000 words
Beginning Readers: Elementary, 5-8; from 500 – 1,500 words
Chapter Books: Elementary, 7-9, from 4,000 – 12,000 words
Middle Grade Novels, 8-12; from 20,000 – 40,000 words
Young Adult, 12+. from 40,000 – 75,000 words
Format: The basic formats of books published. This is divided into three basic categories:
Board Books, heavily illustrated books generally fewer than 32 pages long and made of durable cardboard stock targeted primarily at preschoolers;
Picture Books, heavily illustrated books generally 32 or 48 pages long; and
Novels, books over 32 pages long with few or no illustrations.
Picture books -- Traditionally, picture books (also called "picture story books") are 32-page books for ages 4-8 (this age may vary slightly by publisher). Manuscripts are up to 1500 words, with 1000 words being the average length. Plots are simple with one main character who embodies the child's emotions, concerns and viewpoint. The illustrations on every page or every other page play as great a role as the text in telling the story.
Easy readers -- Also called "easy-to-read", these books are for children just starting to read on their own (age 6-8). They have color illustrations on every page like a picture book, but the format is more grown-up -- smaller trim size, sometimes broken into short chapters. The length varies greatly by publisher; the books can be 32-64 pages long, with 200-1500 words of text, occasionally going up to 2000 words.
The stories are told mainly through action and dialogue, in grammatically simple sentences (one idea per sentence). Books average 2-5 sentences per page.
See the "Amelia Bedelia" books by Peggy Parish or other "I Can Read" books published by Harper Trophy.
Transition books -- Sometimes called "early chapter books" for ages 6-9, they bridge the gap between easy readers and chapter books. Written like easy readers in style, transition books are longer (manuscripts are about 30 pages long, broken into 2-3 page chapters), books have a smaller trim size with black-and-white illustrations every few pages.
See "The Kids of the Polk Street School" series by Patricia Reilly Giff (Dell) or the "Stepping Stone Books" published by Random House.
Chapter books -- For ages 7-10, these books are 45-60 manuscript pages long, broken into 3-4 page chapters. Stories are meatier than transition books, though still contain a lot of action. The sentences can be a bit more complex, but paragraphs are still short (2-4 sentences is average). Chapters often end in the middle of a scene to keep the reader turning the pages.
Look at the "Herbie Jones" books by Suzy Kline (Puffin) and the "Ramona" books by Beverly Cleary (Morrow).
Middle grade -- This is the golden age of reading for many children, ages 8-12. Manuscripts suddenly get longer (100-150 pages), stories more complex (sub-plots involving secondary characters are woven through the story) and themes more sophisticated. Kids get hooked on characters at this age, which explains the popularity of series with 20 or more books involving the same cast. Fiction genres range from contemporary to historical to science fiction/fantasy; nonfiction includes biographies, science, history and multicultural topics.
Check out some middle grade novels from the list of Newbery Medal winners at your library to get you started.
Young adult -- For ages 12 and up, these manuscripts are 130 to about 200 pages long. Plots can be complex with several major characters, though one character should emerge as the focus of the book. Themes should be relevant to the problems and struggles of today's teenagers, regardless of the genre.
The Outsiders by S.E. Hinton defined young adult when it was first published in 1967; the Newbery Medal award list also contains many worthy titles.
A new age category (10-14) is emerging, especially with young adult nonfiction. These books are slightly shorter than the 12 and up category, and topics (both fiction and nonfiction) are appropriate for children who have outgrown middle grade but aren't yet ready for the themes (fiction) or who aren't studying the subjects (nonfiction) of high school readers.