Arnold Schwarzenegger is calling BS on Donald Trump's reported weight ... and while he ain't sure what the former prez's exact poundage is, Arnold's eyeballs tell him Trump missed the mark by about 100 pounds.
The actor was chatting with Jimmy Kimmel Monday night on the host's first show back since the writers' strike ended ... and since he's all about fitness, Arnold weighed in on the topic of Trump's booking records claiming he's 215 pounds.
Before he took a guess, Arnold gave Trump some advice on how he could lose weight -- a decent one-liner about going for a jog which got a big laugh from the crowd.
Jimmy asks again if Trump's Fulton County jail records are accurate when it comes to his size ... and Arnold has some pretty sarcastic responses for the potential of 215 lbs being legit. In his eyes, Trump might've put a 2 when he really meant a 3.