The standard screenplay format dictates that you use Courier New font. It’s a blocky typewriter font that is sometimes difficult to read.
Ever wonder why this font is industry standard?
Most sources say that it is a holdover from Hollywood’s golden age when scripts were typed on typewriters. Although Hollywood rarely eschews tradition, this isn’t the case.
Courier is a fixed-pitch font, meaning each character or space is exactly the same width. Since standard screenplay format is designed so that one page approximately equals one minute of screen time, consistent character spacing is important.
This way when you finish a massive epic screenplay that spans 200 pages, you can estimate that your audience will have to stay in their seats for over 3 hours.