What reading level is The Cobalt Prince?

The Cobalt Prince by Mark Siegel is at a Level 3-4 reading level. Recommended for Middle Grades readers (Ages 9-12).

What age is The Cobalt Prince appropriate for?

The Cobalt Prince is recommended for Ages 9-12. HootRating: 8LP (Light — Physical). Content flags: Mild Peril, Fantasy Violence.

What genre is The Cobalt Prince?

The Cobalt Prince is fiction. Part of the 5 Worlds series.

Does The Cobalt Prince have any content warnings?

The Cobalt Prince has a HootRating of 8LP (Light — Physical). Content flags include: Mild Peril, Fantasy Violence. On HootRated, every book is rated across four dimensions — emotional, physical, social, and thematic — to help parents make informed choices.

How many pages is The Cobalt Prince?

The Cobalt Prince by Mark Siegel is 244 pages (approximately 8,544 words).

Reviewed by HootRated editorial · Last updated May 18, 2026

The Cobalt Prince

Mark Siegel

The Cobalt Prince

Age Rating, Reading Level & Content Guide

by Mark Siegel

Illustrated by Bouma, Xanthe, illustrator

5 Worlds

Reading Level 3-4 8LP Ages 9-12 Matched Page-Turner

The text is written at a 3rd grade reading level, the subject matter is intended for middle graders (ages 9–12), and the content is mild with minimal sensitive material.

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About This Book

Jessa, Oona, and their new ally Ram Sam Sam race against time to prevent the Cobalt Prince of Toki from launching a devastating attack on Mon Domani. Their daring mission could change the fate of worlds and stop a looming interstellar war. Adventure and bravery light the way in this thrilling second installment.

Themes

Adventure Science & NatureHeroesFriendship Fantasy World-Building

Quick Assessment

This is a Level 3-4 book with mild content intensity. Content themes include mild peril, fantasy violence. Written for readers ages 9-12.

Why we rated The Cobalt Prince 8LP

The Cobalt Prince is written at a Level 3-4 reading level across 244 pages (approximately 8,544 words). Strong independent readers around grade 4.4 can typically handle this book on their own; with parent or teacher support, The Cobalt Prince works for readers up to grade 5.4.

Read aloud, The Cobalt Prince takes about 57 minutes, which fits within a single read-aloud session.

We rate The Cobalt Prince as 8LP ("Light — Physical") because the content sits in the "Mild" range — mild conflict — the kind a child encounters in normal play and sibling life. Across our four dimensions (emotional, physical, social, thematic) the book reads as evenly mild; no single dimension stands out as a concern.

Specific content flags noted by reviewers: Mild Peril, Fantasy Violence.

Thematically, The Cobalt Prince explores adventure, science & nature, heroes, friendship, and fantasy world-building — these threads give the book room to mean different things to different readers.

Good fit for

✓ Children in the Ages 9-12 range — the maturity and attention span match the story's pacing.
✓ Reluctant readers who need fast-paced, hook-heavy stories to stay engaged.
✓ Kids drawn to stories about adventure, science & nature, heroes.