Rate-ups are items that have their drop rate increased for that specific banner – but it doesn’t guarantee that you’ll actually get that item. It just increases the chances of you getting it. Games can have different mechanics in how their RNG works, but most of them follow this order: RNG first decides the rarity rank you get and then decides which item you get among all items with that same rarity rank. So there are actually two drop rates that determine which item you receive: As an example, let’s take a look at how Genshin Impact’s event banner works. This is the list of their rarity base rates:
5-star characters have a 0.6% drop rate 4-star items have a 5.1% drop rate 3-star items have a 94.3% drop rate
Additionally, Genshin Impact has a 50/50 system. This means that you have a 50% chance of getting the rate-up character and a 50% chance of getting another 5-star character (not the rate-up one) – this serves as the specific rate. And when visualized, their character event banner works like this: As a comparison, this is how Genshin’s standard banner system works – it doesn’t have a rate-up. You can notice a significant increase in the specific rate of rate-up items vs non-rate-up items. This increase differs for every game. Some gacha games even offer a 100% specific rate for the rate-up item in their event banners.
