meters

So ive been flying over cities quite abit, I am currently flying over a National Stadium, I was wondering how high I have to fly to get the entire stadium in the frame? is there any calculations or equations i can do to figure this out? or are there any available software or ideas available...

Question: In the Advanced Settings you can choose what unit of measurement you want to use, Imperial or Metric. Being a stupid American I chose Imperial since I generally think in terms of feet, yards and miles rather than meters or kilometers. But in the setting labeled "Distance Limit"...