Today I asked someone about a project: “How long has it been in development, how much did it cost, and how many users does it have?” It occurred to me that while I could probably make a pretty good guess about those numbers for THATCamp, I had never sat down and done the math. So I did. Here it is.

THATCamp has been in development for **five years**, maybe almost six if you count the planning time before the first one. The first day of the first THATCamp was May 31, 2008, so the fifth anniversary is coming up on May 31, 2013. (Ooh, maybe that’s the day to release a commemorative edition of the first t-shirt — the dark blue one with the yellow tent.)

How much has THATCamp (broadly conceived) cost over those five years? It turns out there’s a nice round number: **a million dollars**. That’s a rough estimate, of course, but it’s about right. The Mellon Foundation has given us two two-year grants of approximately $250,000 apiece, so that’s half a million dollars. That money has gone to pay my salary (in full) and parts of the salary of various other people at the Roy Rosenzweig Center for History and New Media and beyond who’ve spent time on THATCamp: designers and developers and sysadmins such as Chris Raymond, Jeremy Boggs, Boone Gorges, Tammie Lister, and Ammon Shepherd and administrators and managers and assistants such as Tom Scheinfeldt, Rebecca Onion, Andy Privée, Jeny Martinez, and Sarah Kahler. The money has also funded my travel budget, which has allowed me go to 19 separate THATCamps (at least!) to teach workshops and to help the organizers. The Mellon money has also gone to fund fellowships for grad students and junior scholars to go to THATCamp, and to pay stipends to reviewers of fellowship applications and to workshop instructors. There have been plenty of other miscellaneous expenses, as well (stickers, stickers, and more stickers).

Most of the other half million dollars has come from the many organizations and individuals who have supported individual THATCamps. We estimate (and it’s a pretty rough estimate) that the average THATCamp costs about $4000 to put on, so if you multiply that by the 105 THATCamps since 2008, you get $420,000. (See the THATCamp Directory for the best THATCamp count.) Added to that $420k are the funds from organizations such as Microsoft Research, the Kress Foundation, and the Council on Library and Information Resources who have given money for fellowships and for other forms of general THATCamp support, so half a million is a fair guess.

How many people has that million dollars over five years benefited? Well, there are just over 5,000 registered users on thatcamp.org, but there have been several THATCamps that either don’t register their participants or don’t host their sites on thatcamp.org, so that number doesn’t include everyone who’s ever been to a THATCamp. The last time I ran the numbers (we don’t collect the data systematically), I figured that the average THATCamp has about 70 people, so if you multiply that by the aforesaid 105 THATCamps, you get 7,350. We get lots of ~~recidivists~~, um, repeat THATCampers, of course, so we might as well split the difference: **call it about 6175 people**. Which means that the humanities and technology community as a whole has spent about $162 per person on THATCamp.

I must say: that’s good value. The average rating of THATCamp’s usefulness is 4.46 on a 5-point scale, and while those evaluations come from a smallish subset (N=728) of people who’ve been to THATCamp (and while I’d love to get us back up over that 4.5 mark), I don’t get the sense that there’s a huge population of people who hate THATCamp and get nothing out of it. Just the opposite.

So that’s the math — at least, my math. I wonder what the math looks like for other digital humanities projects.