The youngest age a child can babysit siblings is approximately 12 to 13 years of age. The 12-to-13 age range represents a benchmark and not an absolute. A number of factors play into identifying the youngest age a child is permitted to babysit siblings, including the maturity level of the intended babysitter.
Other key considerations are the length of time the child is expected to watch over siblings and the age of those siblings. The American Red Cross and similar organizations offer babysitting courses for children, including those who are to tend to their siblings in the absence of parents.