There is not an exact answer to your question because different Yorkie lines grow at different rates. A pup who is tiny at 4 months could end up over standard full grown. Whereas a pup who is a little larger at 4 months may not grow much more. The best way to guess your pup's adult size is to look at a few generations back in your pup's lines. You can also double the weight at 12 weeks and sometimes add a pound. An experienced eye can look at a pup's paw and joint and add that to the equation.
Max was 3 pounds and a few ounces at 16 weeks and he is now 8 pounds, 13 ounces. Over standard. Teddy was smaller, but has filled out to 8 pounds.
