Drop Rate Calculator

WHAT THIS APP DOES NOT DO
It names no game and no title. It does not model pity counters, rate-ups,
guaranteed slots or any other mechanic that belongs to one particular title.
It works out no costs, and it offers no advice on whether to keep going.
You put in a rate and a number of draws, and you get the odds.

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Π Drop Rate Calculator － the break-even number of draws only gets you 63.4%

A 1% rate, drawn 100 times. That is the point where one hit is due on average.
Even so, the chance of getting at least one is only 63.4%.
Of everyone who draws 100 times, 36.6% come away with nothing. More than one in three.

■ Three tabs

▪ From draws － enter a rate and a count: at least once, never once, hits on average
▪ From a target － enter "I want 90%" and get the number of draws it takes
▪ Break-even － enter a rate alone and see what the break-even count really gets you

■ The break-even count is only about six in ten

A 1% rate over 100 draws, 3% over 34, 5% over 20, 10% over 10.
Each is the point where one hit is due on average. Here is what you actually get.

1% over 100 draws 63.4%
3% over 34 draws 64.5%
5% over 20 draws 64.2%
10% over 10 draws 65.1%

As the rate gets smaller, the figure creeps towards 63.2%.
0.5% over 200 draws gives 63.3%; 0.1% over 1000 draws gives 63.2%.
It does not fall at every step, though. The break-even count is rounded up to a
whole number, so 5% lands on exactly 20 draws while 3% is rounded up to 34, and
that extra draw puts 3% at 64.5%, above the 64.2% of 5%.
The value it approaches does not depend on the rate, and it never goes below it.

■ Coming away empty-handed is ordinary

Of everyone who draws a 1% rate 100 times, 36.6% get nothing at all.
Even at 10% over 10 draws, 34.9% get nothing.
Nothing unusual has happened.

■ Reaching 90% takes 2.30 times as many

At a 1% rate, 90% arrives at 230 draws. The break-even 100 is nowhere near.
Reaching 99% takes 459. You get to 90% at 230, then draw another 229 on top.
Clearing the last tenth costs as much as everything before it.

■ A run of misses does not change the next draw

What the app gives you is the chance of at least one hit across the whole run.
However many you miss, the next draw carries exactly the rate it started with.
"It must be due by now" is not something this arithmetic produces.

■ What you get

From draws － at least once, never once, hits on average
From a target － draws needed, the chance at that point, times the break-even
Break-even － break-even draws, at least once, never once
Quick chart － every rate from 10% down to 0.1%, drawn to break-even

■ Features

▪ No account needed. The calculation runs on your device and your figures are never sent anywhere
▪ One screen, no settings page
▪ Japanese and English, by device language
▪ History of the last five calculations
▪ Notes on every tab

Percentages are shown to one decimal place, so a count that falls just short of
a target can still read 90.0%. The arithmetic assumes every draw carries the same
rate and that earlier draws do not affect later ones.

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NISAKE GAME