Where the target lengths come from
The presets are publishing conventions rather than rules: 3,000 words for short fiction, 30,000 for a novella, 80,000 for a standard novel, 120,000 for an epic. Those figures reflect what acquiring editors expect by category, which is why they matter commercially even though nothing enforces them.
Adult genre fiction clusters near the novel figure, with fantasy and science fiction running longer and category romance shorter. The number that matters for a submission is the one for your specific category, and a manuscript far outside it is the most common structural reason for an early rejection.
Daily targets, and the arithmetic of finishing
The projection is remaining words divided by your daily rate, and it defaults to 1,000 words a day. That figure is achievable and is also roughly double what most working novelists average once revision, research and days off are included.
The projection assumes you write every day at a constant rate, which nobody does. Use it to compare scenarios — what a 500-word day does to the finish date against a 1,500-word one — rather than as a delivery date. Enter a realistic rate rather than an aspirational one, or the tool will quietly tell you what you want to hear.
It also counts drafting only. Revision is not a fixed fraction of drafting time and is frequently longer.