Word count divided by reading speed gives a useful baseline. At 250 words per minute, 1,000 words takes about four minutes of uninterrupted reading.
Academic reading is slower
Dense arguments, equations, annotation, and note-taking can double or triple that baseline. Preview headings first, then choose a pace that fits your purpose.
Writing includes more than drafting
Separate research, outlining, drafting, revision, references, and proofreading. The Reading Time Calculator and Essay Length Calculator provide useful starting estimates.