Since Ven looks identical to 15 year old Roxas, we can assume that Ven is 15 during the story of BBS. It was said by Nomura that Terra is the oldest, and Aqua is older than Ven, but Younger than Terra.

 

Considering how muscular Terra is, i'd say he's probably 18 or 19. And since Aqua is younger than Terra, i think she's probably 17 or 18.

I was thinking Terra was about 25, Aqua about 23, and Ventus 15. 

That is what I think, I see Terra and Aqua as more of parental figures to Ventus instead of older siblings, and with that logic I see them a decent aging apart.

I would believe Ven is 10 years older than Sora. Terra is 18 or 19 since Xemnas is suppose to be in his early 30's. Aqua is a year younger than Terra.

I never assumed any of them were older than 20 at the time of BBS

I thought this Ventus is either 15 or 16

Aqua is probably 19 or 21

Terra 21 or 23

I always thought it was Ven 16

 Aqua 17-18

  Terra 18-20

I mean terra and aqua are taking the mark of mastery exam at the same time, so they cant be more than 2 years apart at max. I would assume one year or they are the same age. Ven I always thought of as being the same age as sora when he started his journey in kh1 -15. but when I go back and look closer a little older...16 maybe? but I cant really imagine him being any older than that.

Ventus seems to be 15, just like Sora/Roxas. And Terra... well, it's stated that Xemnas is about 30, right? So it would be logical if he would be ~20, because 10 years plus would be 30. And that was the time when Terranort became a heartless. And Aqua... well, 18. You don't need to be older to be wiser, and Aqua's that... in my opinion.

in BBS Ventus is 16 Aqua is at least 18 and Terra is 19 in my order. 

Since Xemnas is in his early 30s, that means Terra was about 19, Aqua was about 18 and I would imagine Ventus is about 14/15.

Sora looks like Roxas and Roxas looks like Ventus, so I assume Ventus is 14-15 like the others said.  Terra and Aqua's ages are ambiguous, but I personally peg them in their early twenties.  Compare Aqua to Kairi and Namine and Xion--she looks much older than them (she's more... er... developed), more along the lines of Larxene.  Larxene seems to be roughly as old as Axel, who, if he was around Ventus's age in BBS, should be around 25 come KH1.  Terra is supposed to be older than Aqua, so he'd of course be one of the older guys.

Ventus is 11, Aqua and Terra are 12. This is the truth, which cannot be denied. Sorry guys.

All jokes aside, I think Ventus is about 16, Terra and Aqua are either 20 - 21

Edited June 22, 201312 yr by PublicLibraryx

How is Ventus 16...? I mean if Sora was 14 in Kiingdom Hearts 1, they look about the same size so I think it's safe to assume they're the same age. Aqua and Terra don't look like they're in their 20s either. I'd say under 20 for both of them. C'mon guys  :mellow: .

Edited June 22, 201312 yr by Drones

I'd wager 17 to 20 for Terra and Aqua, they act fairly mature when it matures. Though Terra is painfully naive sometimes, so that kind evens things up a little women tend to be more mentally mature a lot faster than men. So just going by a mix between their physical appearances and personalities its safest to assume they're young adults no older than 20. 

 

Ventus is a given 15 at least.