So, some people have probably noticed by now that I put phrases like "young adult" or "mature adult" on my ref sheets
Well, I've done quite a bit of comparison between when certain developmental things happen for humans and horses (first tooth, first words, when they're considered an adult, etc)
So, I made a much more complicated chart that laid out the average life expectancy of a human, and a horse, and compared and contrasted with what we know of the pony world...and it looked much too complex, so I whittled it down to this. XD

I don't believe this is the kind of ages they're working with on the show. This is just what I'm using for my own worlds and headcanons.
I'm not saying that anyone else should use this as their age/time basis, but since we've seen ponies developing faster than humans on the show, I believe this is a fitting comparison for my purposes.
(example: the Cake's babies saying what we believe to be their first words at one month old, when the average human infants start saying their first words around 18 months)

Side note: I do not intend to ever have my characters say something like "I'm ten years old now, I should be treated like an adult!"
The purpose of this chart is more to help avoid awkward, confusing dialog like that, while at the same time, providing some evidence of time passing that people may not have been able to guess at before.

If you'd like to use this comparison chart for your own works, feel free to link back to it, but please do not re-upload
Here is the blank template for anyone who may need it: http://mythpony.deviantart.com/art/.....lank-665896234