While there are always exceptions, an ideal length for an adult trade novel is between a minimum of 70,000 words (280 pages) and 90,000 words (360 pages), written in 12 point Times New Roman type. Though chapter length can vary widely, a typical length is 20 typewritten pages at approximately 250 words per page. Generally, the number of chapters range from ten to fifteen. The nature of the material and the desired pacing should suggest how long it will take to shape the scene or to reach a plot point.
Many writers produce between two and five pages a day. Assuming you write two pages a day, five days a week, you’ll have about 40 pages per month in rough draft form. So, it might take about seven months to rough out the shorter novel. However you are probably a long way from finishing the work. Add another three to five months for refining the story before sending it to an editor or agent. Even if you are fortunate enough to land an agent or publisher you can expect more suggested edits.
Keep writing!