Chihuahua weight range is 2-6 pounds. All Chis are in the Toy breed category. There is not a teacup category. It is just a term that some breeders do to entice buyers who want to buy smaller Chis. Some here will tell you that their babies were sold as "teacup" and they are nice, healthy 6 pound babies at full grown.
The chart is accurate for some of us (it is for me) but not at all for others.
According to the chart, he is 34 ounces. It shows that he may be about 5 pounds.