A 1,200 word essay is approximately four to five pages. A double-spaced, one inch margin page contains approximately 250 words.
Whenever instructors or professors give a page number range rather than a word-count range, it's important to check with them to be sure their standards are being met. However, if the instructors set a word count, the only factor altering the number of pages will be formatting. Instructors will know what font, font size, spacing and justification settings they require.
A good rule of thumb for essay length is to keep introductions under one page, to make each body point about a page long and to have the conclusion roughly the same length as the introduction.