Gaming · Calculator

Drop Rate Calculator

Calculate repeated-attempt drop probability and reverse drop-rate targets.

Drop chance per attempt%AttemptsTarget chance for reverse calc%

Chance of at least one drop

63.6%

36.4% chance of no drop across 50 attempts

Probability by Attempts

Series	Label	Value
At least one	1	2%
At least one	5	9.6%
At least one	10	18.3%
At least one	20	33.2%
At least one	50	63.6%
At least one	100	86.7%

Expected attempts for one success

Drop rate for 90% within 50 attempts

4.5%

Export data

Game engine export

Copy or download this result as clean data for your pipeline.

TargetFormat

{
  "id": "drop-rate-probability",
  "name": "Drop probability by attempt count",
  "description": "Cumulative probability of at least one successful drop after a number of attempts.",
  "suggestedVariableName": "dropProbabilityTable",
  "metadata": {
    "dropChancePercent": 2,
    "expectedAttempts": 50
  },
  "columns": [
    {
      "key": "attempts",
      "label": "Attempts",
      "type": "number"
    },
    {
      "key": "dropChance",
      "label": "Drop chance per attempt",
      "type": "number"
    },
    {
      "key": "cumulativeChance",
      "label": "Cumulative chance",
      "type": "number"
    },
    {
      "key": "expectedAttempts",
      "label": "Expected attempts",
      "type": "number"
    }
  ],
  "rows": [
    {
      "attempts": 1,
      "dropChance": 2,
      "cumulativeChance": 2,
      "expectedAttempts": 50
    },
    {
      "attempts": 5,
      "dropChance": 2,
      "cumulativeChance": 9.6079,
      "expectedAttempts": 50
    },
    {
      "attempts": 10,
      "dropChance": 2,
      "cumulativeChance": 18.2927,
      "expectedAttempts": 50
    },
    {
      "attempts": 20,
      "dropChance": 2,
      "cumulativeChance": 33.2392,
      "expectedAttempts": 50
    },
    {
      "attempts": 50,
      "dropChance": 2,
      "cumulativeChance": 63.583,
      "expectedAttempts": 50
    },
    {
      "attempts": 100,
      "dropChance": 2,
      "cumulativeChance": 86.738,
      "expectedAttempts": 50
    }
  ]
}

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How to use this calculator

Calculate repeated-attempt drop probability and reverse drop-rate targets.

How the calculation works

Enter drop chance per attempt and number of attempts.
See probability of at least one drop and no drop.
Use reverse mode to find the per-attempt chance needed for a target probability.

Formula

Chance of at least one = 1 - (1 - drop chance)^attempts.

Example

A 2% drop chance over 50 attempts gives about a 63.6% chance of at least one drop.

Understanding your result

Use the output as a practical starting point, then review it before using it in an important workflow.

Game engine export

This gaming tool can export the visible result as structured JSON or CSV, plus text-based Unity, Unreal, and Godot snippets. The export is generated in your browser from the current result and is meant as a clean starting point for prototypes, balancing sheets, and engine-side data tables.

Assumptions and limitations

The model assumes independent attempts.
Pity timers or dependent loot systems need separate modeling.

Frequently asked questions

Does this require an account?

No. The core tool works without creating a Tool2Do account.

Is my input included in share links or analytics?

No. Tool2Do share actions use the tool page URL and safe metadata, not private values or uploaded files.