age of my snake

Question
QUESTION: I have an albino California king snake and it is about 15 inches long, she eats one pinky every 5 days, how old do you think she might be.

ANSWER: They grow at such different paces, I would guess 18 months. I have one that is 4 years old and is still less than 36 inches long.

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QUESTION: how long approximate are king snake when they are born?  

Answer
Based on my experience, Kingsnakes range from 10 to 15 inches as a hatchling but seem to grow slowly compare to other colubrids. Mine eats every 2 week (appropriate sized prey, 2 or more). Assuming that yours was 12.5 inches at birth, it is reasonable for him to grow 3 to 6 inches in 12 to 18 months. Again, there are so many variables, it is really hard to tell an exact age.