My biceps were 15.5" pumped in this photo - at their biggest, my biceps were 16.7", flexed and pumped [I was 195-lb at that time, as opposed to around 175-lb in this photo].
I suspect that Mark Wahlberg's arms are at LEAST 16" in the photos attached below. They may be in the 17-18" range, given that he does not have Mr. Olympia levels of body fat [he claims 6.9% body fat in the photos below, but I'm not so sure about that].
Mark has always had good genetics for bodybuilding, and was actually considering being a pro bodybuilder in 1993, while he was between his White rapper, and model stage, and before his Hollywood career took off. I read that maybe in 2001, when I ordered his "Form, Focus, Fitness" VHS from EBAY.
It could just be the shape of his arms making them look so big...but I would be surprised if his biceps measured any lower than 17" pumped/flexed.
The last photo was from Mark's underwear model days [1992], and I could see his biceps being smaller during that time, maybe around 15" or thereabouts, at a weight of around 170-lb.