I think one of the first questions new writers ask themselves is: how long should my book be?
The easy answer is: however long you want it to be!
Believe it or not, there are not hard and fast rules to writing a novel. There is no set number of chapters, pages, or words you novel has to be. I remember my novel writing professor in community college give us an example as a short chapter by William Faulkner's As I Lay Dying. It reads "My mother is a fish". That's it. That's the entire chapter. On the other hand, J. R. Tolkein wrote a chapter in The Lord of the Rings with other 16,000 words. Actually, you don't even need set chapters. Just look at Cujo by Stephen King. No set chapters, only scene breaks. [Fun fact: King wrote a one word chapter in Misery that simply reads "Rinse".]
It best to remember that writing is an art form. And your novel is your masterpiece. Like all good art, form and structure are up for interpretation and only limited by your imagination.
But if you've never written a novel before, it's best to have a goal in mind. That is where industry standards come in. Please remember, that industry standards are NOT hard and fast rules. They ARE great benchmarks to keep in mind though.
Here are a few ranges to know!
Short story: under 7,500 words
Novelette: between 7,500 and 17,500 words
Novella: between 17,500 and 40,000 words
Novel: over 40,000 words
Picture Book: 500-600 words
Children’s Book: 1,000-10,000
Middle grade Book: 20,000-50,000 words
Young Adult Novel: 40,000-80,000 words
Once you know what type of book you are writing, then you can take a peak at word count averages by genres:
Fantasy: 110,000 words
Sci-fi: 98,000 words
Action/Adventure: 96,000 words
Mystery/Thriller: 91,000 words
Horror: 100,000 words
Romance: 91,000 words
Historical: 100,000 words
As for my epic fantasy novel, I project my word count to be around 200,000 words (each chapter is expected to average between 4,000 and 4,500 words and I have plotted out 46 chapters). If my daily word count goal is 2,000 words, then I should hit my goal in roughly 3 1/2 months. That doesn't mean my book will be finished. I might still have several chapters to complete when I hit my projected word count. In that case, the ranges I listed should be used for benchmarks for final drafts since the editing process typically lowers total words counts.
Final thoughts?
Don't worry about your word count, just write and see there the story takes you. You will find, even when you plot out your story, some things occur in the moment and you won't know it until you are writing.