I get asked more times than I can count and honestly the answer is simpler than most people make it — aim for 20–30% of your total word count and you're in the right zone. For a 5,000 word paper that's around 1,000–1,500 words, for a 10,000 word dissertation you're looking at 2,000–3,000, and for a 15,000 word one closer to 3,500–4,500. The percentage is your anchor, not a fixed number of someone made up.
The bigger thing people miss is that word count means nothing if the content isn't doing the job - your literature review needs to critically engage with existing research, show the gap your work addresses, and flow into your methodology naturally. A focused 1,800 words that does all that will always beat a padded 3,000 that's just summarizing sources. Always check your specific guidelines first and let quality lead the way