How to use this calculator
Use this for generic card packs, blind boxes and other fixed-rate pulls. Enter the published rate for the exact outcome you want. A rarity category rate is not necessarily the rate of a particular item. Each pack must have the same chance, independently of earlier packs. Collated boxes, guaranteed slots, changing pools and limited inventories need a different model.
The formula
1 − (1 − 1/N)ⁿ
Here p is a probability from 0 to 1, n is a whole number of attempts, C(a,b) counts combinations, and ∏ means multiply all the factors. The input labels define the other symbols.
A worked example
A 1-in-36 rate over 36 independent packs gives about 63.73%, not a guarantee.
Does this predict what I will get?
No. It describes a probability under the rules you enter. A single run can differ from the average. A displayed rounded 100% may still be slightly below certainty unless the model includes a guarantee.
Where do the rates come from?
You enter them. Check the rules and rate disclosure for your exact outcome. We do not supply odds for real products, collect account details or fetch rates from a game or seller.