How is the chance worked out?
For a 1-in-N object the chance of missing it on one roll is 1 - 1/N, so after n rolls the chance of having pulled it at least once is 1 - (1 - 1/N)^n.
Build a Base RNG Roll Odds Calculator
Pick an object and a roll count. The maths uses the base rate the game displays during a roll, so it answers the question players actually ask: how many rolls until I can stop expecting this to happen.
Pick a target
Luck stacks from the skill tree, index completion, the group reward, shop boosts and clover pickups — an endgame player was observed at 1,749x. Those multipliers improve the real rate, so the numbers here are a worst case, not a prediction.
Result
0.66%
chance of seeing Metal Block at least once in 100 rolls
- Average rolls needed
- 15,000
- Rolls for 50% confidence
- 10,397≈ 8h 15m
- Rolls for 90% confidence
- 34,538≈ 1d 3h
- Rolls for 99% confidence
- 69,076≈ 2d 6h
Hitting the average does not mean the item is guaranteed — at that point you are only about 63% likely to have it. Plan against the confidence rows instead.
FAQ
Build a Base RNG Roll Odds Calculator FAQ
I have rolled the average number of times and still have nothing. Is that normal?
Yes. At the average you are only about 63% likely to have seen it. That is why the calculator also shows the counts for 50%, 90% and 99% instead of a single number.
Does luck change these odds?
It changes your effective rate, not the object's base rate. The figures here assume no luck bonus, so with boosts running you should beat them.