2 answers
I don't have kids but after 8 years driving around the city I can tell you it really depends on where you live, if it's a safe neighborhood or not.
most people I know let their kids go alone around 10 or 11 years old, but some wait until they're 12 or 13, it all depends on whether the kid is responsible and knows the route well.
personally I think you gotta let them go eventually because otherwise they never learn to fend for themselves, but yeah, first you gotta make sure the route is safe.
How do you guys measure if your son is ready? Because age is the least of it; what really matters is whether he knows how to cross a street without getting distracted, if he knows the route well, and if he has a phone to let you know. My trick is doing a couple of runs together before letting him go solo, but paying attention to how he handles corners and whether he's actually looking around instead of staring at his screen. That tells you way more than any birthday ever would.
Your answer
Log into answer.