Why is my chance still not 100% after many runs?

Each attempt is independent, so the drop never becomes guaranteed unless a pity or bad-luck-protection system exists. The chance of missing every time is (1 - p) raised to the number of attempts, which shrinks but never reaches zero.

How do I convert a 1 in 100 drop to a percentage?

Divide 1 by the number and multiply by 100. A 1 in 100 drop is 0.01, or 1%. This tool accepts either format so you can paste whichever a database lists.

What does at-least-once probability mean?

It is the chance you get the item one or more times across all your attempts. It equals 1 minus the chance of getting it zero times, which is the most useful number for farming.

How many runs do I need to be reasonably sure?

For a 1% drop you need about 69 runs for a 50% chance, 230 for 90%, and 459 for 99%. The tool computes these thresholds for your exact drop rate using ceil(ln(1 - target) / ln(1 - p)).

Does a higher drop rate guarantee fewer runs?

On average yes, but RNG means some players still get unlucky streaks. The cumulative odds describe the distribution across many players, not a promise for any single run of attempts.

World of Warcraft Drop Rate & Probability Calculator

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Drop-rate frustration usually comes from misreading the math. A 1% drop does not mean you are guaranteed the item in 100 kills. This calculator uses the correct probability model so you know your real cumulative odds and how many attempts a given confidence level actually requires.

How it works

Each attempt is an independent Bernoulli trial with success probability p. The chance of failing every one of n attempts is (1 - p)^n, so the chance of getting the item at least once is:

P(at least once) = 1 - (1 - p)^n

To find how many attempts you need for a target confidence c (for example 0.90), invert the formula:

n = ceil( ln(1 - c) / ln(1 - p) )

This is the geometric distribution. It explains why even very lucky drop rates never give a hard guarantee — the failure term only approaches zero.

Example and tips

A mount with a 1 in 100 (1%) drop gives roughly a 63% chance of dropping within 100 kills, not 100%. You need about 230 kills for a 90% chance and 459 for 99%. Treat the at-least-once figure as your honest expectation, and remember that bad-luck-protection or pity systems, where they exist, change the model entirely — use the Gacha Pity Calculator for those.