A bachelor's thesis, a master's thesis, and a doctoral dissertation are the three main types of academic work you write to complete a degree, and they differ in study level, the original contribution expected from you, length, and the title you earn. A bachelor's thesis completes undergraduate study, a master's thesis (sometimes called a master's dissertation) completes a graduate degree, and a doctoral dissertation (PhD) is the major scholarly output of a doctorate. In Central Europe you may also meet the rigorosum, a separate procedure with its own title, which we cover briefly below. The exact requirements are always set by your institution.
In this article we compare the main thesis types by study level, purpose, expected originality, indicative length, difficulty, and how each is defended, and we explain which type suits whom. For completeness, any length ranges are indicative only. The binding numbers are always in your department's guidelines, which take priority over any general advice.
Thesis types at a glance
The table below summarizes the main differences. Treat it as an orientation map, not a binding standard. Length, difficulty, and the form of defense vary by institution and field, and the exact terms differ between countries.
| Aspect | Bachelor's thesis | Master's thesis (dissertation) | Doctoral dissertation (PhD) |
|---|---|---|---|
| Study level | undergraduate | graduate | doctoral |
| Typical outcome | bachelor's degree (e.g. BA, BSc) | master's degree (e.g. MA, MSc) | doctorate (PhD) |
| Purpose | show command of the basics of the field | show you can tackle a problem independently | contribute genuinely new knowledge |
| Original contribution | smaller, applying existing knowledge | clearer, your own research | original scholarly contribution |
| Indicative core length | usually shorter | usually longer than a bachelor's | usually the longest |
| Difficulty | foundational | intermediate | highest |
| How it is defended | defense or examination, where required | defense or examination, where required | defense (viva), plus published output in many systems |
We deliberately avoid quoting exact page or word counts. Every institution has its own rules and the differences between fields are large. A technical thesis with extensive code in the appendices has a different "length" than a theoretical thesis in the humanities. There is only one reliable source of numbers, and that is your own department's guidelines.
A note on the word "dissertation" before we go further. In British usage, "dissertation" often refers to the longer project at bachelor's or master's level, while "thesis" is reserved for the doctorate. In American usage it is usually the reverse: a "thesis" at master's level and a "dissertation" for the PhD. The words point to the same kinds of work; what matters is the study level, not the label.
Bachelor's thesis: your first independent academic text
A bachelor's thesis is the final project of undergraduate study. After you pass, you earn a bachelor's degree such as a BA or BSc. For most students it is the first longer piece of academic writing they produce entirely on their own.
The aim of a bachelor's thesis is to show that you have grasped the foundations of your field, can work with academic literature, and can present it clearly. The original contribution expected from you is smaller. The focus is on applying existing knowledge, writing a solid review, and doing a basic analysis of your own data or a case study.
The methodology in a bachelor's thesis tends to be simpler and the sample smaller. That is perfectly fine; what matters is that the methodology is present and justified. If you are unsure how to organize the whole text logically, our guide to how to structure a thesis will help.
Master's thesis: solving a problem on your own
A master's thesis (in some systems a master's dissertation) is the final project of graduate study. After you pass, you earn a master's degree such as an MA or MSc.
Compared with a bachelor's thesis, a master's thesis expects a clearer original contribution. The goal is not just to summarize what is known about a topic, but to tackle a specific problem independently. That means your own research, a deeper synthesis of the literature, and a more considered methodology with a larger or better-justified sample.
A master's thesis is therefore more demanding in time, length, and depth. In it you show that you can not only work with sources but also design a study, gather data, interpret it, and draw conclusions. For practical help with the whole process, from topic to final formatting, see our master's thesis service.
Doctoral dissertation (PhD): the scholarly output of a doctorate
A doctoral dissertation is the major work of a doctorate, the highest level of study. After a successful defense (often called a viva), you earn the title PhD, written after your name. In many systems part of the research is also expected to appear as published articles.
A doctoral dissertation has the highest demands of all. Its goal is not to summarize what we already know, but to bring genuinely new findings to the field. A doctoral candidate is therefore expected to make an original scholarly contribution and to defend their results before an expert committee.
The length and depth of the work match that ambition and are usually the largest of all the types. A doctorate takes several years, and the dissertation is its main output. This is why a PhD is widely seen as the most advanced academic qualification.
The rigorosum: a Central European specialty in brief
If you study in Slovakia or the Czech Republic, you may come across the rigorosum, often nicknamed the "small doctorate". It is not a degree-level thesis in the usual sense, but a separate procedure that graduates can undertake after a master's degree. It combines a rigorosum thesis with an oral examination, and on passing the candidate earns a title written before the name, such as PhDr. (humanities and social sciences), JUDr. (law), or RNDr. (natural sciences).
The key distinction is the type of contribution. A doctoral dissertation requires original new knowledge; the rigorosum mainly asks the candidate to demonstrate deeper knowledge and the ability to apply it creatively, without necessarily discovering something new. For a closer look at how the procedure works and which titles it confers, see our article on what a rigorosum, PhDr. and RNDr. mean.
Which type is for whom
Choosing a thesis type is not really a free choice. It follows from your study level and your goal. For a quick orientation:
- A bachelor's thesis is for students finishing undergraduate study. If you are writing your first major academic text and want to show command of the basics, this is your project.
- A master's thesis is for graduate students who already hold a bachelor's degree and are ready to show they can tackle a problem independently with their own research.
- A doctoral dissertation is for those pursuing research who want to contribute new knowledge and earn a PhD.
- The rigorosum is a Central European option for master's graduates who want a title before their name without completing a full doctorate.
If you are still weighing your options or need expert help with any type of work, take a look at our services or get in touch through contact. We are happy to advise on exactly what your project needs.
Frequently asked questions
What is the difference between a bachelor's and a master's thesis?
A bachelor's thesis completes undergraduate study and earns a bachelor's degree. It mainly asks you to show command of the basics and to apply existing knowledge. A master's thesis completes graduate study, leads to a master's degree, and requires a clearer original contribution and independent research. A master's thesis is therefore longer and more demanding.
Is a thesis the same as a dissertation?
It depends on where you study. In British usage, "dissertation" often refers to the project at bachelor's or master's level, while "thesis" is reserved for the doctorate. In American usage it is usually the reverse: "thesis" at master's level and "dissertation" for the PhD. The terms describe the same kinds of work; the study level is what really distinguishes them.
What is a rigorosum and how does it differ from a PhD?
The rigorosum is a Central European (Slovak and Czech) procedure that master's graduates can undertake to earn a title before their name, such as PhDr. or JUDr. It is sometimes called the "small doctorate". Unlike a PhD, it does not require original new findings; it asks the candidate to demonstrate deeper knowledge and the ability to apply it creatively. A PhD, by contrast, requires an original scholarly contribution.
What title do I earn after each type of work?
After a bachelor's thesis you earn a bachelor's degree such as BA or BSc. After a master's thesis you earn a master's degree such as MA or MSc. After a doctoral dissertation you earn a PhD, written after your name. The rigorosum confers a Central European title before the name, such as PhDr. or RNDr. For how titles are ordered and written, see our overview of academic degrees and titles explained.
How many pages should each type have?
There is no general figure; the length is set by your specific institution. As a rule, both difficulty and length grow from a bachelor's, through a master's, to a doctoral dissertation. The differences between fields are large, however, so always follow your department's guidelines rather than generic numbers from the internet.
How does the defense differ between the types?
A bachelor's and a master's thesis are typically defended before a committee or examined, where the system requires it. The rigorosum adds an oral examination in the field. A doctoral dissertation is defended before an expert committee in a procedure (often called a viva) that is more demanding and more research-focused, and many systems also expect published output. The exact process is always set by your institution.