The harder the science, the shorter the length. The humanities, for example History, are the longest. Because they explain with words, and in detail. No surprise there.

Average length of PhD dissertations by major from
dataisbeautiful

A typical dissertation runs between 250 and 300 pages, divided into four or five chapters, often with a short conclusion following the final full-scale chapter.

There is no set minimum or maximum length, but anything below about 225 pages will likely look insubstantial in comparison to others, while anything over 350 pages may suggest a lack of proportion and control of the topic, and would probably take too long to write.

At many German universities, the following rule of thumb applies: achelor’s theses are 40 to 60 pages long, and Master’s theses are around 80 to 120 pages. Some universities also specify the expected scope in words, which is then between 15,000 and 20,000 words.

Still others only specify the processing time, but do not express any limitation in terms of the number of pages or words. Depending on whether you are writing your Master’s thesis in three or six months, you can use the following rules of thumb as a guide: 3 months processing time = 60-80 pages, 6 months processing time = 80-120 pages

University of Houston – Jeremy Bailey Susan Scarrow writes:

A master’s thesis is generally 40-80 pages, not including the bibliography. However, the length will vary according to the topic and the method of analysis, so the appropriate length will be determined by you and your committee. Students who write a master’s thesis generally do so over two semesters.

A master’s thesis is a piece of original scholarship written under the direction of a faculty advisor. A master’s thesis is similar to a doctoral dissertation, but it is generally shorter and more narrowly focused.

As a rule of thumb, a master’s thesis should be publishable as a single article, though it might be longer than a typical article; a doctoral dissertation is generally equivalent to at least three articles.

Students who chose to write a master’s thesis rather than a bibliographic essay often do so because they are interested in pursuing further research, for instance in a doctoral program in political science or another discipline, or as a researcher in a public agency.