Question: how old are the mlp ponies?
Answer: A: The ponies' ages were left intentionally undefined. I like to think of them as having maturity levels anywhere between 12 and 18, (but remember that maturity is different than age. You can be a 10-year-old with the maturity of a 15-year-old, and you can be a 35-year-old with the maturity of a 15-year-old.)