Como dizer "de idade" em inglês

No, it's wrong. You should say "16 years old".

Então:

Persons under 18 years of age travelling by themselves must have their own passports.
(canadainternational)
Não teria que ser “persons under 18 years old”?

Outro:
He made his professional debut for Newell's in 1998, with 18 years of age. (Wikipedia)

Mara Sofia Valente escreveu:No, it's wrong. You should say "16 years old".

Na verdade:
http://fraze.it/n_search.jsp?q=of+age&l=0&sugg=off

About 77080 results found using 'OF AGE'. Source: 'Daily Use'.

At 28 years of age, Freese didn't have forever to establish a big-league career
Today's date is Thursday, October 13, 2011 and I've just turned 31 years of age.
The Mozart Ensemble will be open to beginning students from 4 to 7 years of age.
Must be at least 18 years of age and have a valid Pennsylvania Driver's License.
Classified information is presumed declassified when it reaches 25 years of age.

Boa tarde.

Os fóruns que encontrei sobre o assunto dizem que "years of age" é usado mais formalmente, ou seja, está correto utilizar "years old" ou "years of age".

Segue link:
http://forum.thefreedictionary.com/post ... age--.aspx

Abraços.

Diego has it right.