In 2006 two Chihuahua sisters are from the same litter, same mother and father, born same day, same age. Notice the vast difference in size of the sisters. I predicted 3 on the tiny sister and 6 on the larger sister
These sisters were sold in 2006 . Final outcome?
The teeny tiny puppy 12 oz 11 week old went to 6 lbs! The much larger sister went to 4 lbs.
So it appears "obvious" who would be the smaller Chihuahua adult?? Not always as we learn here.
Although this particular outcome went against the grain and is not the common outcome for the puppy sizes you see, this true example should prove to you that if any breeder promises an exact adult size based on the weight and size of a young puppy, they are either taking you for a ride or are very inexperienced novices and have much yet to learn. The photo of " Lambchop" with her owner was taken when she came back to me to buy another Chihuahua. She did not hold a grudge for my mistake.

Sisters same litter, same mother and father, same age. Did you read the story about the consumer who asked me to guarantee the tiny puppy ( on the left) would not go over 3 lbs? I refused to guarantee that because I will not base love and acceptance of my puppies on ounces of weight . The consumer went on her way and what happened on her quest for a "breeder" who would provide her with a "guaranteed" Teacup Chihuahua? THE STORY OF SHERBERT
I predicted Sherbert to be 3 lbs or under and I predicted 5 lbs grown on the larger sister I called Monroe.
Final outcome n Sherberts size ? The teeny tiny Chihuahua puppy "Sherbert" went to the 2 lb range and the larger girl went to a few oz over 3lbs. I kept Monroe for breeding so I was a bit unhappy she did not make it to 4 lbs.

In 2006 my puppy MOOKIE was born and she was a huge puppy. The largest puppy I have every produced. I had never had a puppy that weighed nearly 3 lbs at 10 weeks old. I breed 3 lb adults! So I was confused and figured she must be a "throw back" from past generations. I was afraid to sell her because I was known for having smaller Chihuahuas. I did though place her online and mentioned that she was a huge gorgeous "mutation" in size from her ancestors. Then as Mookie was over 3 lbs at 3 month old I became alarmed so removed her from my website. What if she grew to be 10 lbs I imagined? It was totally foreign to me to have a puppy this size and I honestly did not know what to make of it. I imagined someone walking down the street with MOOKIE as a 12 lb Chihuahua and people stopping to ask where such a Chihuahua was bought... and the buyer would say 'Munchkinland Chihuahuas.... So I was having these scary thoughts and pulled her off my website, but someone had fallen in love with her !
A customer of mine who had a 3 lb adult she had bought from me a year ago wanted Mookie and I simply told her I couldn't sell the puppy because she could end up a very unusual size. My customer laughed and insisted to purchase. When MOOKIE was going on one year I got a phone call from the buyer to inform me that Mookie was just about 5 1/2 lbs. So much for my Mookie The Giant ......
TWO SISTERS GO AGAINST THE GRAIN!
THE CASE OF SHERBERT AND MY REFUSAL TO GUARANTEE HER ADULT SIZE