What age do you think you become an adult?

Not when the law says your an adult.
I think it varies widely from personality to person and depends on when somebody becomes accountable for their own schedule and responsible for their own well being. For some this is young, approaching 18. For other people it may never happen. They remain in a abnormal adolescent phase until they grow too old and become childlike again. Honesty, at 15 !
My parents moved away i got a employment and lived with my grandparents who were "clueless" about the tangible world.
the first few weeks i did what ever i wanted - parties, nudity, drinking etc., afterwards i realized where is this life taking me! School started again and i did better than i ever have before, i learned to cook at home with my grandparents, painted their house, and volunteered at my grandparents church. Life feel so meaning full - i was accomplishing my goal
18, the law has it right because the law is where on earth you become an adult. You can't enter into a contract, and are very limited within work rules until 18. You can't survive on your own for the most part until 18. Now if the law changed it's age then I'd agree beside the new age of the law. Being an adult is roughly surviving on your own, and without the help from the law you can't. You become an fully fledged when you can take care of yourself and provide for your own means of living.

That technique moving out, buying your own food, gas, paying your own rent, and saving some money for a rainy day.

It is taking on the responsibilites of living individually and inside societies rules. By being a good citizen, living independently, and respecting the laws of the country than you become an mature.

Going off to college is not yet being an developed unless you are paying your own way through school and not depending upon the state, or your parents. College is one step along the way to grown hood, but not the only one.
i think i become an adult when i can drive (16). i can walk places by myself and be out on my own more often. The age where reason define your decisions.
Legally or emotionally? Legally, in the US, it's 18. Emotionally...it varies. I've known teenagers who enjoy been very mature and learned way beyond their years, and then some grown adults in their 30's and 40's who still perform like little children. I'd say late twenties to nearly 30. I think when people turn 21 they think they can do anything and are still not sure of what they want to do and haven't figure out lots of things and who they really are. This is only some people...lots of people, I regard as.
I construe when youre able to take responsibilty 4 ur self. some ppl nevr become an adult. Otherwise around ur behind schedule 20's.
I dont think within is a certain age that you become an adult. I think you become an developed when you are mature & responsible. People might not become that till they are like 30. The legal age is 17...if you budge to court, you are charged as an adult if you are 17 years of age.
21 I guess it is age 21..
i think it's 16, u know "sweet 16" for Jewish people it's 13, for Mexicans it's 15. 18
when your maturity level matches your age. There are so several so called adults out there that act so childish....and vice versa. There is no exact number that declare a person as an adult....but legally speaking....18. When you stop asking yourself that cross-question and start asking - "what happened to my childhood?". THAT will be when you finally know.

I'm not kidding - you'll see.
27...by after u should be done w/school...away from mommy and daddy and have ur head outa ur ***...