Type your wins and losses per trading day and get a 95% interval that counts days as the evidence, next to the one every other calculator prints.
Two 95% intervals on the same win rate. The first treats every trade as an independent draw, which is the arithmetic behind "a hundred trades is enough". The second resamples whole trading days with replacement, two thousand times, and reads the interval off the result. It is the same code that computes every interval a FillStub subscriber sees, and it refuses below 5 days for the same reason the product does. Why the day is the unit is the long answer.
Nothing you type is stored. The numbers travel in the address of this page and nowhere else, which is also why a result can be linked to. Up to 250 days and 5000 trades per request.