How to prepare for a PhD viva

What the viva is testing

The PhD viva voce is a spoken examination of your thesis and your ability to defend it. Examiners have read your work carefully, and they will ask questions about the decisions you made — your research question, your methodology, your findings, your interpretation, your claims about contribution. They are testing not just what you know, but how well you understand your own work.

The examination is usually two to three hours long. It is typically between you and two examiners — one internal and one external. The questions will range broadly across your thesis, but often spend significant time on methodology, contribution, and limitations. There is no fixed script. The conversation goes where the examiners take it.

Read your thesis with examiner questions in mind

One of the most useful preparation activities is reading your thesis again — not as the author, but as an examiner. At every significant decision point, ask: why did I do this? What alternatives did I consider? What are the limitations of this choice?

This is the mode of reading that prepares you for the questions you are actually likely to receive. If you chose a particular methodology, an examiner will ask why. If you excluded a body of literature, they may ask about it. If your findings suggest a particular interpretation, they may ask whether another interpretation is possible.

Prepare your contribution, methodology, limitations, and future work

There are four areas that come up in almost every viva, and it is worth preparing each one deliberately:

• Contribution: Can you state precisely what your thesis adds to the field? Not in vague terms, but with specificity. What would researchers not know without this work?
• Methodology: Why this approach? What alternatives did you consider? How did you ensure rigour? How do the method's limitations affect your conclusions?
• Limitations: Every thesis has them. Being able to name yours precisely, explain their scope, and place them in context is important. Examiners expect you to know your own limitations — being surprised by them is worse than acknowledging them clearly.
• Future work: What should be done next? What questions does your thesis open up? This is often asked near the end of the viva and rewards genuine intellectual engagement with the direction of the field.

Practise out loud

This is the part of viva preparation that most candidates underestimate. Knowing your thesis well is necessary but not sufficient. The viva is a spoken examination, and articulating ideas out loud is a distinct skill from knowing them in your head.

When you explain your methodology out loud, you find the points where your reasoning isn't yet crisp. When you respond to a follow-up question in real time, you build the flexibility the viva demands. This is not something you can prepare for by reading.

Spoken rehearsal — whether with a colleague, a supervisor, or a practice tool — is one of the most effective preparation strategies available. If you can only do one thing to prepare beyond reading your thesis, make it spoken practice.

Use mock viva rehearsal

A formal mock viva with your supervisor is excellent preparation if you can arrange one. The challenge is that it is difficult to do more than once, and the bar to arranging it can be high.

Supplementary private rehearsal — practising the spoken conversation multiple times, in low-stakes settings — gives you additional preparation time that doesn't depend on coordinating schedules. The aim is to make the viva conversation familiar before exam day, not to achieve perfection in a single session.

Defensia provides real-time mock viva practice grounded in your thesis — an AI examiner that asks questions from your specific work, listens to your spoken answers, and follows up on them. It is designed to give you additional rehearsal time between formal mock vivas.

Prepare calmly in the final week

In the final days before the viva, consolidation is more useful than new preparation. Re-read your thesis, make sure you can state your contribution clearly, and review your methodology chapter. Do one or two shorter practice sessions to stay familiar with the spoken format.

Avoid trying to master new material in the final days. Trust the work you have done over the previous weeks and months. The viva is where you demonstrate that you understand your own work — and the best way to do that is to have engaged with it deeply enough that it feels natural to discuss.

How Defensia can help

Defensia gives you a real-time spoken mock viva based on your uploaded thesis. You upload your work, choose an examiner style, and take part in a live session — answering out loud, responding to follow-ups, and receiving structured feedback at the end.

It is most useful as part of a broader preparation plan — alongside reading your thesis, talking through your work with colleagues, and arranging a formal mock with your supervisor where possible. It is not a replacement for any of those things, but it gives you private, on-demand rehearsal time that is otherwise hard to find.