There are very few states in the U.S. with legal minimum ages for children home alone, but many state agencies have published guidelines. Georgia, Illiniois, Maryland and Oregon are a few of the states with specific ages mentioned in their laws.
12 years of age appears to be the most common recommendation. Below in Related Links is an article entitled Home Alone Children Legal Age Limits state by state comparison with references.
One guideline from a California child welfare representative suggests that 8 year olds and over can be left at home for a brief amount of time(such as just after school). The most common statement is that a child's maturity should be the determining factor and not just age.
ADDED STATEMENT-in new zealand the legal age is 12. you can babysit when you are 14.
8 IS TOO YOUNG!
You are aloud to stay home alone when you're 12-13. Also, make sure you take safety precautions like not lighting candles and locking the doors. Be sure a parent or friend has their cell phone with them also.