Bongo Cat Chest Simulator
Open chests at Steam's published odds and watch the gap between the average and what actually happens. Averages promise a Legendary eventually; this shows how long 'eventually' can run.
Chest Simulator real published odds
Tier probabilities are Steam’s published drop-pool table (Common 90% → Legendary 1 in 500,000, marked “subject to change” on the store page), used verbatim. Which item you get inside a tier is drawn uniformly — that part is our assumption, because Steam publishes the tier rate only and never a per-item chance. This is a simulation for understanding spread; it does not read your inventory and cannot predict your next chest.
An expected value of 1.0 is not a guarantee
Every drop-rate table invites the same arithmetic: Epic is 0.01%, so 10,000 chests should hand over one Epic. The expectation really is 1.0 — and it is also true that about 36.8% of players who open exactly 10,000 chests still have none. Both statements come from the same number. Only one of them gets repeated.
The reason is that each chest is independent, so the chance of a complete miss is (1 − rate)^chests. Push the tier rate down and the chest count up in equal measure and that expression settles at 1/e, roughly 36.8%, for every tier — Rare at 0.49% over 204 chests, Legendary at 1 in 500,000 over 500,000. The drought is not bad luck specific to you; it is the shape of the distribution.
How to read your chest simulator run
The tally counts what you pulled. The table underneath answers the more useful question: given how many chests you have opened, what share of players would still be empty-handed on each tier? When your count is zero and that number is high, nothing has gone wrong. When your count is zero and that number has fallen into the low single digits, you are genuinely on the unlucky tail.
Two things this tool deliberately does not do. It does not quote a probability for a specific item — Steam publishes tier rates only, and with 12 Legendaries a per-item figure would be invented. And it does not touch your account: the rolls happen in your browser and vanish when you reload.
Where this fits with the other tools
The rarity drop calculator turns playtime into expected items per tier, and the drop rates page lays out the published table itself. Both work in averages. This page is the counterweight: the same odds, played out one chest at a time, so the spread around those averages stops being abstract. If you are weighing a pile of duplicates instead, the trade-up planner works in certainties — ten of a tier become one of the next, no luck involved.
Questions
If Epic is 0.01%, am I guaranteed one in 10,000 chests?
No. Opening 10,000 chests gives an expected 1.0 Epic, but the chance of still having none is (1 - 0.0001)^10000, which is about 36.8%. Roughly one player in three sits at zero after opening the "average" amount.
Does the simulator use the real Bongo Cat drop rates?
Yes for the tier probabilities: Common 90%, Uncommon 9.5%, Rare 0.49%, Epic 0.01%, Legendary 1 in 500,000, taken from the drop-pool table Steam publishes on the Bongo Cat store page and marked there as subject to change. Those five values sum to 100.0002%, so they are not a valid distribution: the simulator draws from the rarest tier down, which gives every rare tier exactly its published probability and leaves Common absorbing the 0.0002 percentage-point overhang (89.9998%). Which item you receive inside a tier is drawn uniformly, which is an assumption on our part — Steam publishes the tier rate only, never a per-item chance.
Can the simulator predict my next chest?
No. It does not read your Steam inventory and has no connection to the game. Each roll is an independent random draw in your browser, which is exactly why it is useful for seeing variance rather than for forecasting.