* Reading speed: People read at vastly different speeds. Some might read 120 pages in an hour, while others might take 3 or more.
* Complexity of the text: A dense, academic text will take longer to read than a simple novel.
* Level of comprehension: If you're reading for detailed understanding, it'll take longer than if you're skimming for general information.
* Distractions: Interruptions and distractions significantly impact reading time.
To get a personal estimate, time yourself reading a chapter or two and extrapolate.