I determine my rates based on level and length of the manuscript for content editing. (wordwebbing.com)
You'll see that we request all the salient elements typically found in a query letter: the title, premise, and length of the manuscript, your writing background, and your long - term writing plans. (serendipitylit.com)
The length of your manuscript (obviously, you're going to pay more for a 150,000 word novel than a 70,000 word novel). (aliventures.com)