How Old Do You Have to Be to Enter Sweepstakes?
Eighteen is the usual answer in the United States, and the exact figure is always stated in the official rules rather than assumed.
Why eighteen
A winner signs an affidavit and a liability release, which is a contract, and minors generally cannot be bound by one. Some promotions set the minimum at nineteen or twenty-one to match the age of majority in particular states or the nature of the prize.
Where under-eighteen entry exists
Some promotions accept entries from minors with a parent or guardian entering on their behalf and receiving the prize. Where that is allowed, the rules say so explicitly, and where they are silent, it is not permitted.
What happens if an underage entry wins
It is disqualified at verification and the company running it redraws. There is no version of this where the prize is awarded anyway, so entering under the stated age spends effort for a result that cannot arrive.