Hold old are these people supposed to be?!

In the scene in the end, where they show Lilo blowing out some birthday candles, they're seven candles so she must have been six for most of the movie.

Lilo is 5 years old, that's what I read in one of the official disney magazines, Nani is 19 yeras old and David is 23 years old

Lilo has got to be somewhere between the ages of 5-7. Yes she does talk like a grown-up, but I can't imagine anyone over five years of age riding tricycles. I bet a four year old can do that, but not anyone at five years. Maybe she's short for a kid so she has to be like "42 to ride a bicycle.

Sonic will be hearty forever.
"Mom, could I get one of these?" - Little Girl

I just watched this on demand for the first time. In the end when they show the cake there are 7 candles on it which means Lilo is 6. Here in Hawaii there is always an extra candle for good luck on our cakes. It is a local custom among all of my friends and their families too.

The tricycle brand is called a Big Wheel, they came in several sizes. Suitable for ages 3-8, says it on the box. I had one when I was a kid, a 7 year old could ride it just fine.

If you look at the trivia section they have this

Lilo is 6 in the film. Daveigh Chase who voiced her was 9 when she started.

So Lilio would be 6 for most of the film, expect for the very end of the movie, and if you remember their parents are dead, so who is really going to teach Lilo how to ride a bike, her sister Nani is seen working, and you have to assume that she is supposed to a be a teenager. Myrtle and the other girls my best guess would be about the same age as Lilo or maybe a few years older then her. But there is the only mention of how old Lilo is, and not on any of the other characters, so you kind of have to wonder if they couldn't come up with an age for the other characters in the movie.

You'd be surprised at how some 5 and 6 year olds can be, verbally. Lilo talks a lot with her sister, and tends to be around adults a lot (going to Nani's work, etc). Also, with few friends, she spends a lot of time reading and has odd interests.
I remember having a conversation with a 6 year old once. I was doing face painting at a party, and she wanted a heart on her face. I asked her what color and she responded. "Black, like my soul!"
When my friends younger son was 6, he probably could have held his own in conversation with a Titanic expert about that boat, he knew so much and could speak so intelligently on it.

Please, people, don't get Big Wheels mixed up with "tricycles". Yes, a Big Wheel is a tricycle, but ...

The tricycles that used to predominate just never seemed to get up any speed.

Big Wheels, on the other hand, just seemed to fly along, and kids can get them to skid sideways to a stop just as Stitch did a time or two when trying to "zero in on a big city" and got to the coast instead.