Length wise, A Black Throat Monitor can grow to be between three and seven feet long(1 or 2 meters). Three to three and a half feet is the norm for these reptiles, but if you do as directed and insure they receive all of the minerals they need and you take VERY good care of them- they'll outsize three feet sufficiently.
Weight wise, Between 20 and 65 lbs. It varies by how you feed them. If you feed them dog food, with is very high in calories, they'll get plump, not big, and weigh a lot. Obesity. Not good. Weight should vary by length. A six foot lizard should be 50 to 65 lbs. A three foot lizard should be 15 to 20 lbs.