What sizes are small and medium? Age wise

Small is ages 4-6 years old, and Medium is ages 8-10 years old

Which size should I order for a 7 year old who is a little tall?

size small: 4-6 years. size meduim 8-10 years

What size for a bigger 7 year old boy, not skinny about 4 feet

Got a small for 4 year old who is very tall and thin. He wears a 6. Medium for 9 year old who is short and a bit thicker. He wears 10-12. They will be a little long. Like most dress up clothes a little looser.

Does this costume run big?

I was worried about the sizing before my purchase too. I was torn between getting a small or medium. I ended up buying medium size 8-10. My son is normally a size 6/7, he's 52 pounds and 5yrs old. The small fits up to a size 6 and I was worried it might be an exact fit or a tight fit. I went ahead and got the medium and I'm happy I did. He looks great in it. It's a little big but I folded it one time at the waist. Once you put the belt on u can't tell that the pants are folded. And I folded it around his wrist as well. He tends to wear his customs around the house to play even after Halloween so this is perfect because he has room to grown and keep wearing it :) also the belt is pretty big. Once the belt is clipped on, the left over loose end actually wraps around to his back :/ thankfully, the holes on the belt are very big. u can use anything to put through the holes and tie it, just so it's in place and not hanging down in their way. I used the little bread ties ;) that's normally used to close up slice bread. But really u can use anything. I hope this was helpful :)