When you are writing your first novel, you don't have the experience of having written a long work of fiction before.
Yes, I know that's kind of obvious, but here's the point...
Like I said, if you have written a book before, experience will tell you the answers to these questions.
But if you are writing your first novel, you will need to trust your instincts and take an educated guess.
You have read plenty of novels before (I hope!) so you must at least have some sense of how much raw material it takes to fill a few hundred pages of a book.
But the problem continues even after you have finished the planning and you are ready to start actually writing your first novel.
Let's say you are going to aim for 80,000 words, which is a good, sensible target (see the article on Novel Length for more).
To achieve this target, you will need to fill about 350 manuscript pages. So you start writing your novel...
So, how do you go about hitting the perfect novel length if you are writing your first novel?
The first thing to say is that, without experience, judging the eventual length of a novel while you are still writing it is next to impossible.
The best advice I can give is to not worry about length at all when you are writing the first draft stage. Simply write the novel as you think it should be written and see what you end up with...
The second time you write a novel, with this experience behind you, you will be able to better judge the word count from the outset. When you are writing your first novel, you are going to have to trust your instincts and see where they take you.
All of which is true - but not very helpful!
I need to offer you more specific advice on judging the length of a novel as you plan and write it, and here it is...
Novel length is not determined by the size and complexity of your plot, or even the number of characters, so much as how you portray the events.
Okay, the eventual size of a novel obviously has something to do with the plot...
In the article on Plotting the Novel's Middle, I said that the middle section of a novel can be compared to getting from one side of a river to another.
Well, if your river is on the small side - more of a stream, in fact - there will obviously be less steps involved in crossing from one side to the other than if your river is the mighty Mississippi.
Also, the greater number of subplots that your novel contains - particularly those told from the viewpoints of other characters - the longer that novel is likely to be.
Nevertheless, the biggest determinant of a novel's length is not what you say but how you say it.
To illustrate this, think of a man stroking a cat...
This simple action can be described in the simplest of sentences: "Fred stroked the cat."
At the other end of the scale, it is perfectly possible to take 20 pages, or even 200 pages, to describe it - if you mention everything that Fred senses and everything he feels emotionally and every thought and memory that passes through his mind as he strokes the cat.
And it is the same with every event in a novel...
Either option will be open to you, and it is how you decide to pace the novel - when to speed things up or even omit them altogether, when to slow things right down again with fuller descriptions, lengthier dialogues, and so on - that will ultimately determine its length.
And, yes, that means that a novel's length is determined by how much you show and tell...
(Follow this link for more on Writing a Narrative By Showing and Telling.)
If you are writing your first novel, you will have to trust your instincts during the planning and drafting stages as to whether the novel will end up at the right length.
The size of your plot (how many scenes your novel contains) has some influence on novel length, as do the number of characters, though not as much as you might think.
When plotting, don't think about "how much" plot you need to make the novel an acceptable length - think about how much plot you need to tell the story.
It is how much of the novel you "show" and how much you "tell" that ultimately counts. Again, you will have to trust your instincts here - if a scene feels like it should be fully written (showing), write it that way. If not, deal with it concisely by telling.
Once you have completed the novel, and you know how much you need to add or subtract, you will then be able to use these two devices - the amount of plot, and how you have portrayed the events of the plot - to adjust the length of the novel accordingly.
One last tip on writing your first novel...
Having your novel end up too long is always better than having it finish too short.
Reducing a novel in size when you revise it is much easier than having to bulk it out. Bulking it out can lead to "padding" the novel, and that is never artistically satisfactory.