Drop Rate & Loot Table Calculator

Why "1%" does not mean "once in 100 tries"

Each try is independent, so a 1% item can take far more than 100 tries. The chance of getting at least one drop after n tries is:

1 − (1 − p)^n

With a 1% drop rate, only about 63% of players get the item within 100 tries, and the unluckiest 1% need more than 459. That is why players complain about "bad luck", and why showing the real odds helps you choose fair drop rates.

Quick reference

Designing loot tables with weights

• Give common items large weights (like 100) and rare items small ones (like 1).
• Adding a new item only needs a new weight; the other percentages adjust automatically.
• To roll: pick a random number between 0 and the total weight, then walk through the items adding their weights until you pass the number.
• In Unreal Engine, store weights in a DataTable. In Unity, a ScriptableObject with a list of items and weights works well.

Pity systems and bad-luck protection

If a rare item matters for progression, pure randomness will frustrate a few unlucky players every time. Common fixes:

• Hard pity: guarantee the drop after a fixed number of failures. The "tries for 99%" number above is a good starting point.
• Soft pity: increase the drop chance a little after every failure.
• Shuffle bags: put all outcomes in a bag and draw without replacement, so the rare item is guaranteed once per bag.
• Duplicates protection: re-roll or convert duplicates into currency.

Be transparent: many players, platforms and some regions expect drop rates for paid random items to be disclosed.

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