Islamically, الحج is واجب (فرض) only for those who have reached puberty (bulugh), are of sound mind, and meet other conditions of obligation. A child who has not reached puberty can perform الحج, and it is valid as a voluntary (nafl) act of worship, but it does not count as fulfilling the واجب الحج — they must perform الحج again after reaching puberty. النبي Muhammad (صلى الله عليه وسلم) confirmed this when a woman lifted her child and asked if the child could perform الحج.
المملكة العربية السعودية sets its own administrative requirements which may include minimum ages for visa issuance. Children must be accompanied by parents or legal guardians and should be included in the family's الحج application. Some countries have their own age restrictions for الحج registration.
There is no maximum age limit in Islamic law for الحج. However, Saudi authorities may issue health advisories or guidelines for elderly الحجاج. Elderly individuals should obtain thorough medical clearance before applying. If a person is too old or ill to perform الحج themselves, they may delegate someone to perform الحج on their behalf (الحج badal), provided they have the financial means. This proxy must have already performed their own واجب الحج first.