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Kordu Tools

Drop Rate Calculator

Calculate loot drop probabilities, expected farming runs, and dry streak odds. Enter any drop rate and see exactly how many attempts you need for 50%, 90%, or 99% confidence.

Results for 100 attempts

At least one drop

63.40%

Dry streak (0 drops)

36.60%

50% confidence

69 runs

90% confidence

230 runs

99% confidence

459 runs

Probability curve

40%
51
63%
100
64%
102
79%
153
87%
204
92%
255
95%
306
97%
357
98%
408
99%
459

Attempts

Quick reference — attempts needed at 1% drop rate

ConfidenceAttempts
50%69
75%138
90%230
95%299
99%459

Assumes each attempt is independent with a fixed drop rate. Does not account for pity systems, bad luck protection, or pseudo-random distribution that some games use.

How to use

  1. 1

    Enter the drop rate

    Type the item's drop rate percentage into the input field, or click a preset button (50%, 10%, 5%, 1%, 0.1%, 0.01%) for common rates.

  2. 2

    Enter your number of attempts

    Type how many attempts, kills, or runs you want to calculate for. Leave it blank to see just the confidence table and chart.

  3. 3

    Read your results

    View the probability of at least one drop, the dry streak chance, and expected attempts for 50%, 90%, and 99% confidence — all updated live as you type.

  4. 4

    Check the probability curve

    Scroll down to see a visual chart showing how your drop probability grows with each attempt, with your entered attempt count highlighted.

Frequently asked questions

How is drop probability calculated?
The probability of getting at least one drop in N attempts is P = 1 - (1 - r)^N, where r is the drop rate as a decimal. This assumes each attempt is independent with the same drop rate — the standard model for loot drops in most games.
What does 'dry streak probability' mean?
Dry streak probability is the chance of getting zero drops across all your attempts. It equals (1 - r)^N. For example, with a 1% drop rate and 100 attempts, there is about a 36.6% chance you get nothing at all.
Why do I need so many attempts for a 99% confidence drop?
Probability approaches 100% asymptotically — it never truly reaches it. Going from 90% to 99% confidence requires roughly the same number of additional attempts as going from 0% to 90%. This is why rare drops can feel so punishing.
Does this work for any game?
Yes, as long as each attempt has the same independent drop rate. This covers most RPGs, MMOs, gacha games, and looter shooters. It does not account for pity systems, bad luck protection, or dynamic drop rate adjustments some games use.
What if my drop rate is something like 1/256?
Convert the fraction to a percentage first: 1/256 = 0.390625%. Then enter 0.390625 in the drop rate field. The calculator handles any decimal precision.
Is a 1% drop rate really that bad?
With a 1% drop rate you need 69 attempts for a 50% chance and 459 attempts for a 99% chance of at least one drop. Many players underestimate how many runs rare items actually require.

Find out exactly how lucky (or unlucky) you are with the Drop Rate Calculator.

Enter any drop rate percentage and number of attempts to instantly see the

probability of getting at least one drop, the chance of a complete dry streak,

and how many runs you need for 50%, 75%, 90%, 95%, and 99% confidence. A live

probability curve visualizes how your odds improve with each additional attempt,

so you can decide whether that next farming run is worth your time. Preset

buttons for common drop rates (50%, 10%, 5%, 1%, 0.1%, 0.01%) let you jump

straight to popular scenarios. Every calculation runs entirely in your browser

with zero latency — no sign-up required, no data sent to any server.

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