Your question is simple, but the answer isn't. It depends on several factors.
1. Where do you live? City? Suburbs? Rural area? How far away will you be, how long does it take for EMS to arrive?
2. How is your neighborhood? Do your kids know your neighbors and do you trust them?
3. How long are you thinking of leaving them? You have to start somewhere...
4. How mature are they? Do you have more than one child? Ages?
We live in a very safe, small city in a very safe suburban neighborhood. The kids both ride the bus to and from school. I started leaving them home for about 1 hour to go to the grocery store at about age 8 and 9, with strict instructions and a call at the 30 minute mark. I built on that hour over time. The next school year, they started coming home from school and staying alone until I got home from work (about 1 hour and 45 minutes). They were required to call me upon arrival at home. I continued to build on that until my husband and I could go out for a date and I could trust that they would watch a movie, get ready for bed, and be in bed either sleeping or reading when we arrive home.
Today they are 10 and 11 (almost 12). They can stay the whole day on their own if school's out because we worked on it and they know the rules.
The rules:
1. No cooking. If you're hungry, make a sandwich or eat something that doesn't require cooking.
2. Don't leave the house unless there is an emergency. In an emergency, go to Mr. Chad's house next door and call me.
3. Don't let anyone in.
These were the rules when we started, but now they've changed because they have matured. So now the rules are:
1. No cooking on the stove. Don't leave the microwave unattended. Use potholders. The fire extinguisher is by the fridge.
2. You may play outside as long as you call me and tell me where you'll be, and check in occasionally.
3. Don't let anyone in.
Hope that helps!
♥
C. Lee
ETA: A land-line phone is required. Kids need to be able to call 9-1-1 and have your home address pop up immediately for the dispacher, in case they call and cannot speak, or call and are forced to hang up. Cell phones do not do this because it takes time for GPS location to get to dispach (and not all systems have this capability).