do u know whats weird? no one really knows how old ash is. so im holding a poll to see how old he is. (ur opinyoun)
i say 14 because of the weird voice and all.... (puberty) can u imagin ash as a mans voice?
It's unknown. In the anime, it doesn't tell you, but he began as a 10-year old. Common sense shows he is most likely around 12 or 13 by now. 
He doesn't seem to be growing much at all, does he? He looks just as shrimpy as he did in the first episode.
If it when by real life years, he'd be about 20-some years old, if he was 10 years old in 1996. =P But, he's around 13 or so, probably.
I always go by this. He was 10 years old when he started, right?
Kanto: 1 or 2 years (Now 12)
Johto and the Orange Islands: 1 year (13)
Hoenn: 1 or 2 years (15)
Sinnoh: Not done, but give or take another year of the series and he's 16
That's just my personal way of looking at it. :3
However old he is, Ash needs to stop picking up random 10 year old girls.
But I seeing somewhere that he was about 13.
Lol @ above.
I reckon he's about 13 too. There are a few things that contradict in the anime when it comes to time passing, but one solid piece of evidence is that he celebrated his first year with Pikachu in Pokemon 3 (mid Johto). That makes him 11. By mid-Hoenn he was probably around 12 and I'd say he's getting close to 13 now.
I pretty much agree... Ash is like about 13... or so...
His looks confuses me... o_o
I don't really know...
But I'd estimate between 15 and 16 years old...
Why? Voice change; end of.
ID SAY HES ABOUT 17 OR 13 BUT IT WOULD B COOL IF HE HAD A BIRTHDAY IMEAN COME ON HE REMEMBERS ABOUT WEN HE FIRST MET PIKACHU BUT HE CANT EVEN CELIBRATE HIS OWN BIRTHDAY THATS SAD KINDA U KNOW