Loot Table Calculator

Check the probabilities for a loot table made of multiple items, using either Weighted Roll or Independent Roll.

Roll Mode

Each roll picks exactly one item from the table. Each item's chance is its Weight divided by the total Weight.

Load a Sample

Number of Rolls

rolls

3 / 50 rows

Results

Item	Chance per Roll	1/x	At Least 1 by Roll Count	Chance of None	Expected Count

What is the Loot Table Calculator?

This tool designs and checks the probabilities for a loot table made of multiple items. For each item, you can see the chance per roll, the chance of getting at least one over a number of rolls, and the expected count — all in one table. It supports up to 50 items, with 1 to 1,000,000 rolls.

How to Use

Choose a Roll Mode (Weighted Roll or Independent Roll).
Enter the number of rolls as a whole number from 1 to 1,000,000.
Enter an item name and either a Weight (Weighted Roll) or a Drop Rate % (Independent Roll). Use "+ Add Item" to add up to 50 rows.
Press "Calculate" to see a table of each item's probability and drop chance.
Copy the result if needed. Load a sample to try an example right away.

Independent Roll vs. Weighted Roll

Weighted Roll picks exactly one item from the table on each roll. Each item's chance is its Weight divided by the total Weight, so the probabilities always add up to 100%. This fits a draw where "something is always received," like a treasure chest or a gacha pull.

Independent Roll checks each item separately with its own drop rate. A single roll can produce multiple items at once, or none at all, and the probabilities can add up to more than 100% without any issue. This fits a per-item drop system, like a monster's loot drops.

Example

With Weighted Roll, for a table of Common 60, Uncommon 25, Rare 10, Epic 4, and Legendary 1 (total 100) rolled 10 times, the Legendary chance is 1%. The chance of getting at least one over 10 rolls is about 9.56%, and about 65.13% for Rare.

With Independent Roll, checking a Potion at 50%, a Rare Part at 20%, and a Rare Weapon at 5% in a single roll, the chance of getting nothing is 0.5 × 0.8 × 0.95 = 38%. The chance of getting at least one item is 62%, and the expected item count per roll is 0.75.

Using This in Game Development

When building a treasure chest or boss reward table, you can check whether each rarity's Weight produces the intended probability. For a monster's drop settings, looking at the chance of getting nothing and the expected item count per roll helps tune farming pace and reward volume. Changing the roll count also gives a sense of how many runs a player needs to reasonably get a rare item.

Difference from the Drop Rate Calculator

The Drop Rate Calculator calculates the chance of obtaining an item, or the number of attempts needed to reach a target chance, from a single item's drop rate and number of attempts. The Loot Table Calculator is for designing and checking an entire table made of multiple items — converting Weight to probability, checking the total probability, and handling the chance of getting nothing. If you want to know in detail how many attempts it takes to get one specific item, use the Drop Rate Calculator instead.

Notes

Each roll is assumed to be independent, with the same probabilities every time. This tool does not model a pity system, guaranteed slots, rate-up mechanics, or weights that change between rolls. In Weighted Roll, an item with a Weight of 0 never appears. The expected count is an average and does not guarantee the actual number obtained. Extremely small probabilities are shown in a simplified form, such as "Less than 0.000001%."

FAQ

What's the difference between Weight and Drop Rate (%)?

Weight is a relative ratio against the other items; dividing by the total gives a probability. Drop Rate (%) directly represents the chance of that single item appearing on its own.

Do the Weights need to add up to 100?

No. They can add up to any value. Keeping them at 100 just makes it easy to read each Weight directly as a percentage.

Is it fine for Independent Roll's probabilities to add up to more than 100%?

Yes, that's fine. Since each item is checked separately, a total above 100% just means multiple items are more likely to appear in the same roll.

Does a 100% item become a guaranteed drop?

In Independent Roll, an item with its Drop Rate set to 100% always appears on every roll. This tool has no separate feature dedicated to guaranteed drops.

Can I enter a decimal value for Weight?

Yes. Any value from 0 up to 1,000,000,000, including decimals, can be entered.