As part of adherence to Chinese law, Blizzard Entertainment has revealed the odds of receiving various items in Overwatch loot crates as well as those for its other games. In Overwatch, on average every crate will contain a blue (rare) item, a purple (epic) every 5.5 boxes and a legendary in every 13.5 boxes.
Other Blizzard game odds on average:
- Heroes of the Storm: Rare - every crate; epic - every 4.5 crates; legendary - every 17.5 crates
- HearthStone: Rare - every pack; epic - ever 5 packs; legendary - every 20 packs
These are the average odds in China, though it remains to be seen whether or not this is the same for all regions.
Via Kotaku