One of the things about being married to a minister is that I sometimes end up helping with resources. And so it was that I was asked how many tears someone would cry in a lifetime, for use as an illustration in a service.
This turns out to be a difficult question. If you just count tears of sadness, then of course it depends on how often you are sad, and how sad, as well as how long you live. But I ended up with a sort of answer, and although it was on the internet, it wasn’t found through a regular internet search.
I started with a regular internet search, for something like “how many tears are cried?”. That brought up a lot of news stories, which give widely different figures, with no sources.
The chain of research then went something like this:
These alerted me to the three types of tear (possibly a medical textbook would have told me that too). Equipped with alternative search terms, I headed for PubMed. I found this, searching for basal tear flow.
I then went back to Google, but Google Scholar. I searched for basal tears volume, and along with the Farris article cited above, I found this from the British Journal of Ophthalmology from 1953. That cites this 1903 paper by Schirmer. I had no access to the full text of this but looking for it in Google finds this related article by De Roetth from the AMA Archives of Ophthalmology (related because it also cites Schirmer).
De Roetth cites Schirmer but also mentions that Schirmer is citing work by Ahlstrom (also a related article to Schirmer in Google Scholar - 1895. Ahlström, Über die antiseptische Wirkung der Tränen. Zentralbl. f. Augenheilk. S. 193).
I had no access to Ahlstrom either but de Roetth gives Alhstrom's figure (as well as describing the limitation of Ahlstrom’s method, which might mean the figure is too high). The figure was 4 grams of basal tears a day. De Roetth was not available in full online, but the first page, with this information, was.
I then made an assumption that 1g of tears was 1ml in volume, which was, I think, quite close, and another assumption about how long our hypothetical person would live. Taking that as 80 years gave 4 x 365 x 80 ml of tears, which is 116.8 litres of tears in a lifetime.
So, an answer for illustrative purposes.
And not a new answer. A figure from 1895, cited in 1903, with that paper cited in 1953. Although it did come up in an internet search, it was not found straight away.