Average Viva Lengths

I once took survey responses from over 300 PhD graduates about their viva experiences. There was a lot of data and a lot of clusters within the data. Without being careful it would have been easy to share wrong ideas about what was “average” or “normal”.

What might average mean? If we added up all of the viva lengths and divided them by the number of people it came to around 2 hours and 20 minutes.

Was that average though? Was that normal? What could I share that was useful?


In the end, thinking more on the data and on what people asked me I came to share a few key points about the average viva length:

  • Every viva is unique, so knowing an “average” doesn’t help by itself.
  • Sharing a breakdown of percentages doesn’t help either, it’s too much!
  • Expectations are useful to help in preparation: so an expected length has to be useful.

Which leads me to say: expect your viva to be at least two hours, because around 50% of vivas are two hours or longer. Yours could be less, but if you expect it to be longer then you can prepare to engage for a long period of time. You can prepare to take your time – and if it’s shorter then at least you’ll be well-prepared, rather than simply hoping it is over quickly!

And perhaps we should dismiss the notion of “average” vivas completely. There are real expectations we can explore for the viva, but they cover ranges of experiences rather than simple numbers.